Durable anti-reflective articles

ABSTRACT

Embodiments of durable, anti-reflective articles are described. In one or more embodiments, the article includes a substrate and an anti-reflective coating disposed on the major surface. The article exhibits an average light transmittance of about 94% or greater over an optical wavelength regime and/or an average light reflectance of about 2% or less over the optical wavelength regime, as measured from an anti-reflective surface. In some embodiments, the article exhibits a maximum hardness of about 8 GPa or greater as measured by a Berkovich Indenter Hardness Test along an indentation depth of about 50 nm or greater and a b* value, in reflectance, in the range from about −5 to about 1 as measured on the anti-reflective surface only at all incidence illumination angles in the range from about 0 degrees to about 60 degrees under an International Commission on Illumination illuminant.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation application of U.S. Ser. No. 14/707,106 filed May 8, 2015, now pending, which claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application Ser. No. 62/098,836 filed Dec. 31, 2014, U.S. Provisional Application Ser. No. 62/098,819 filed Dec. 31, 2014, U.S. Provisional Application Ser. No. 62/028,014 filed Jul. 23, 2014, U.S. Provisional Application Ser. No. 62/010,092 filed Jun. 10, 2014, and U.S. Provisional Application Ser. No. 61/991,656 filed May 12, 2014, the contents of which are s relied upon and incorporated herein by reference in their entirety.

BACKGROUND

The disclosure relates to durable anti-reflective articles and methods for making the same, and more particularly to articles with multi-layer anti-reflective coatings exhibiting abrasion resistance, low reflectivity, and colorless transmittance and/or reflectance.

Cover articles are often used to protect critical devices within electronic products, to provide a user interface for input and/or display, and/or many other functions. Such products include mobile devices, such as smart phones, mp3 players and computer tablets. Cover articles also include architectural articles, transportation articles (e.g., articles used in automotive applications, trains, aircraft, sea craft, etc.), appliance articles, or any article that requires some transparency, scratch-resistance, abrasion resistance or a combination thereof. These applications often demand scratch-resistance and strong optical performance characteristics, in terms of maximum light transmittance and minimum reflectance. Furthermore, some cover applications require that the color exhibited or perceived, in reflection and/or transmission, does not change appreciably as the viewing angle is changed. In display applications, this is because, if the color in reflection or transmission changes with viewing angle to an appreciable degree, the user of the product will perceive a change in color or brightness of the display, which can diminish the perceived quality of the display. In other applications, changes in color may negatively impact the aesthetic requirements or other functional requirements.

The optical performance of cover articles can be improved by using various anti-reflective coatings; however known anti-reflective coatings are susceptible to wear or abrasion. Such abrasion can compromise any optical performance improvements achieved by the anti-reflective coating. For example, optical filters are often made from multilayer coatings having differing refractive indices and made from optically transparent dielectric material (e.g., oxides, nitrides, and fluorides). Most of the typical oxides used for such optical filters are wide band-gap materials, which do not have the requisite mechanical properties, such as hardness, for use in mobile devices, architectural articles, transportation articles or appliance articles. Nitrides and diamond-like coatings may exhibit high hardness values but such materials do not exhibit the transmittance needed for such applications.

Abrasion damage can include reciprocating sliding contact from counter face objects (e.g., fingers). In addition, abrasion damage can generate heat, which can degrade chemical bonds in the film materials and cause flaking and other types of damage to the cover glass. Since abrasion damage is often experienced over a longer term than the single events that cause scratches, the coating materials disposed experiencing abrasion damage can also oxidize, which further degrades the durability of the coating.

Accordingly, there is a need for new cover articles, and methods for their manufacture, which are abrasion resistant and have improved optical performance.

SUMMARY

Embodiments of durable, anti-reflective articles are described. In one or more embodiments, the article includes a substrate and an anti-reflective coating having a thickness of about 1 μm or less (e.g., about 800 nm or less) disposed on the major surface forming an anti-reflective surface. The article exhibits an abrasion resistance as measured on the anti-reflective surface after a 500-cycle abrasion using a Taber Test, as described herein. In one or more embodiments, the article exhibits an abrasion resistance (as measured on the anti-reflective surface) comprising about 1% haze or less, as measured using a hazemeter having an aperture, wherein the aperture has a diameter of about 8 mm. In one or more embodiments, the article exhibits an abrasion resistance (as measured on the anti-reflective surface) comprising an average roughness Ra, as measured by atomic force microscopy, of about 12 nm or less. In one or more embodiments, the article exhibits an abrasion resistance (as measured on the anti-reflective surface) comprising a scattered light intensity of about 0.05 (in units of 1/steradian) or less, at a polar scattering angle of about 40 degrees or less, as measured at normal incidence in transmission using an imaging sphere for scatter measurements, with a 2 mm aperture at 600 nm wavelength. In some instances, the article exhibits an abrasion resistance (as measured on the anti-reflective surface) comprising a scattered light intensity of about 0.1 (in units of l/steradian) or less, at a polar scattering angle of about 20 degrees or less, as measured at normal incidence in transmission using an imaging sphere for scatter measurements, with a 2 mm aperture at 600 nm wavelength.

The article of one or more embodiments exhibits superior optical performance in terms of light transmittance and/or light reflectance. In one or more embodiments, the article exhibits an average light transmittance (measured on the anti-reflective surface) of about 94% or greater (e.g., about 98% or greater) over an optical wavelength regime (e.g., in the range from about 400 nm to about 800 nm or from about 450 nm to about 650 nm). In some embodiments, the article exhibits an average light reflectance (measured at the anti-reflective surface) of about 2% or less (e.g., about 1% or less) over the optical wavelength regime. The article may exhibits an average light transmittance or average light reflectance having an average oscillation amplitude of about 1 percentage points or less over the optical wavelength regime. In some instances, the article exhibits an angular color shift of less than about less than about 10 (e.g., 5 or less, 4 or less, 3 or less, 2 or less or about 1 or less) from a reference illumination angle to an incident illumination angle in the range from about 2 degrees to about 60 degrees, when viewed at the anti-reflective surface using an illuminant. Exemplary illuminants include any one of CIE F2, CIE F10, CIE F11, CIE F12 and CIE D65. In one or more embodiment, the article may exhibit a b* value of in the range from about −5 to about 1, from about −5 to about 0 or from about −4 to about 0, in the CIE L*, a*, b* colorimetry system at all incidence illumination angles in the range from about 0 to about 60 degrees. Alternatively or additionally, the article of some embodiments exhibits a transmittance color (or transmittance color coordinates) and/or a reflectance color (or reflectance color coordinates) measured at the anti-reflective surface having a reference point color shift of less than about 2 from a reference point, as defined herein. In one or more embodiments, the reference point may be the origin (0, 0) in the L*a*b* color space (or the color coordinates a*=0, b*=0), the coordinates (a*=−2,b*=−2) or the transmittance or reflectance color coordinates of the substrate. The angular color shift, reference color shift and color coordinates (a* and/or b*) described herein are observed under a D65 and/or F2 illuminant.

In one or more embodiments, the anti-reflective coating may include a plurality of layers. For example, in some embodiments, the anti-reflective coating includes a period comprising a first low RI layer and a second high RI layer. The period may include a first low RI layer and a second high RI disposed on the first low RI layer or vice versa. In some embodiments, the period may include a third layer. The anti-reflective coating may include a plurality of periods such that the first low RI layer and the second high RI layer alternate. The anti-reflective coating can include up to about 10 periods.

In one or more embodiments, at least one of the first low RI layer and the second high RI layer includes an optical thickness (n*d) in the range from about 2 nm to about 200 nm. In some embodiments, the anti-reflective coating includes a plurality of layers with one or more second high RI layer(s) such that the combined thickness of the second high RI layer(s) is less than about 500 nm or less.

In some embodiments, the article may include a layer having a refractive index greater than about 1.9. Materials that may be utilized in that layer include SiN_(x), SiO_(x)N_(y), Si_(u)Al_(v)O_(x)N_(y), AlN_(x), AlO_(x)N_(y) or a combination thereof.

In some instances, the article may include an additional layer, such as an easy-to-clean coating, a diamond-like carbon (“DLC”) coating, a scratch-resistant coating or a combination thereof. Such coatings may be disposed on the anti-reflective coating or between layers of the anti-reflective coating. Where scratch resistant coatings are included, such coatings may be disposed on the anti-reflective coating and may form a scratch resistant surface. Exemplary scratch resistant coatings may exhibit a hardness in the range from about 8 GPa to about 50 GPa as measured by a Berkovitch Indenter Hardness Test, as defined herein.

In some embodiments, the article may include a layer having a refractive index greater than about 1.9. Materials that may be utilized in that layer include SiN_(x), SiO_(x)N_(y), Si_(u)Al_(v)O_(x)N_(y), AlN_(x), AlO_(x)N_(y) or a combination thereof.

The substrate utilized in one or more embodiments of the article can include an amorphous substrate or a crystalline substrate. An of an amorphous substrate includes glass that may be selected from the group consisting of soda lime glass, alkali aluminosilicate glass, alkali containing borosilicate glass and alkali aluminoborosilicate glass. In some embodiments, the glass may be strengthened and may include a compressive stress (CS) layer with a surface CS of at least 250 MPa extending within the strengthened glass from a surface of the chemically strengthened glass to a depth of layer (DOL) of at least about 10 μm.

Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments as described herein, including the detailed description which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description and the following detailed description are merely exemplary, and are intended to provide an overview or framework to understanding the nature and character of the claims. The accompanying drawings are included to provide a further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the description serve to explain principles and operation of the various embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an article, according to one or more embodiments;

FIG. 2 is a side view of an article, according to one or more specific embodiments;

FIG. 3 is a side view of an article, according to one or more embodiments;

FIG. 4 is a side view of an article, according to one or more embodiments;

FIG. 5 is a side view of an article, according to one or more embodiments;

FIG. 6 is a side view of an article, according to one or more embodiments;

FIG. 7 is a side view of an article according Example 1;

FIG. 8 is a graph showing the reflectance of the article according to Example 1;

FIG. 9 is graph showing the modeled reflectance of the article according to Example 2;

FIG. 10 is graph showing the modeled reflectance of the article according to Example 3;

FIG. 11 is a graph showing the modeled reflectance of the article according to Example 3, with an additional DLC coating;

FIG. 12 is an illustration of an article according to Example 4;

FIG. 13 is a single-sided reflectance spectra of the article of Example 4, showing the reflectance as the incident illumination angle changes from 0° to about 60°;

FIG. 14 is a reflected color spectra of the article of Example 4 showing the reflected color under different illuminants at different viewing angles, using a 10° observer;

FIG. 15 is an illustration of an article according to Example 5;

FIG. 16 is a single-sided reflectance spectra of the article of Example 5, showing the reflectance as the incident illumination angle changes from 0° to about 45°;

FIG. 17 is a reflected color spectra of the article of Example 5 showing the reflected color under a D65 illuminant at different viewing angles, using a 10° observer;

FIG. 18 is an illustration of an article according to Example 6;

FIG. 19 is a single-sided reflectance spectra of the article of Example 6, showing the reflectance as the incident illumination angle changes from 0° to about 60°;

FIG. 20 is a reflected color spectra of the article of Example 6 showing the reflected color under different illuminants at different viewing angle, using a 10° observer;

FIG. 21 is an illustration of an article according to Example 7;

FIG. 22 is a single-sided reflectance spectra of the article of Example 7, showing the reflectance as the incident illumination angle changes from 0° to about 60°;

FIG. 23 is a reflected color spectra of the article of Example 7 showing the reflected color under different illuminants at different viewing angle, using a 10° observer;

FIG. 24 is an illustration of an article according to Example 8;

FIG. 25 is a single-sided reflectance spectra of the article of Example 8, showing the reflectance as the incident illumination angle changes from 0° to about 60°;

FIG. 26 is a reflected color spectra of the article of Example 8 showing the reflected color under different illuminants at different viewing angle, using a 10° observer;

FIG. 27 is a single-sided reflectance spectra of the article of modeled Example 9, showing the reflectance as the incident illumination angle changes from 0° to about 60°;

FIG. 28 is a reflected color spectra of the article of Example 9 showing the reflected color under different illuminants at different viewing angle, using a 10° observer;

FIG. 29 is a single-sided reflectance spectra of the article of modeled Example 10A, showing the reflectance as the incident illumination angle changes from 0° to about 60°;

FIG. 30 is a single-sided reflectance spectra of the article of modeled Example 10B, showing the reflectance as the incident illumination angle changes from 0° to about 60°;

FIG. 31 is a reflected color spectra of the article of Example 10A showing the reflected color under different illuminants at different viewing angle, using a 10° observer;

FIG. 32 is a reflected color spectra of the article of Example 10B showing the reflected color under different illuminants at different viewing angle, using a 10° observer;

FIG. 33 is a graph showing scattered light intensity values measured for Examples 12 and 13 and Comparative Examples 15, 16, and 17 after and without being subjected to the Taber Test;

FIG. 34 is a graph showing the AFM roughness statistics measured for Examples 12 and 13 and Comparative Examples 14, 17 and 18 after being subjected to the Taber Test;

FIG. 35 is a single-sided reflectance spectra of the article of Example 19, showing the reflectance as the incident illumination angle changes from 0° to about 60°;

FIG. 36 is a reflected and transmitted color spectra of the article of Example 19 showing the reflected and transmitted color under different illuminants at different viewing angle, using a 10° observer;

FIG. 37 is an graph showing the measured transmittance color coordinates and reflectance color coordinates of Example 21;

FIG. 38 is the reflectance spectrum for Example 21 at different illumination angles;

FIG. 39 is a graph showing the two surface transmittance and reflectance spectra for Example 21;

FIG. 40 is a graph illustrating the hardness measurements as a function of indentation depth and coating thickness.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying drawings.

Referring to FIG. 1, the article 100 according to one or more embodiments may include a substrate 110, and an anti-reflective coating 120 disposed on the substrate. The substrate 110 includes opposing major surfaces 112, 114 and opposing minor surfaces 116, 118. The anti-reflective coating 120 is shown in FIG. 1 as being disposed on a first opposing major surface 112; however, the anti-reflective coating 120 may be disposed on the second opposing major surface 114 and/or one or both of the opposing minor surfaces, in addition to or instead of being disposed on the first opposing major surface 112. The anti-reflective coating 120 forms an anti-reflective surface 122.

The anti-reflective coating 120 includes at least one layer of at least one material. The term “layer” may include a single layer or may include one or more sub-layers. Such sub-layers may be in direct contact with one another. The sub-layers may be formed from the same material or two or more different materials. In one or more alternative embodiments, such sub-layers may have intervening layers of different materials disposed therebetween. In one or more embodiments a layer may include one or more contiguous and uninterrupted layers and/or one or more discontinuous and interrupted layers (i.e., a layer having different materials formed adjacent to one another). A layer or sub-layers may be formed by any known method in the art, including discrete deposition or continuous deposition processes. In one or more embodiments, the layer may be formed using only continuous deposition processes, or, alternatively, only discrete deposition processes.

As used herein, the term “dispose” includes coating, depositing and/or forming a material onto a surface using any known method in the art. The disposed material may constitute a layer, as defined herein. The phrase “disposed on” includes the instance of forming a material onto a surface such that the material is in direct contact with the surface and also includes the instance where the material is formed on a surface, with one or more intervening material(s) is between the disposed material and the surface. The intervening material(s) may constitute a layer, as defined herein.

The anti-reflective coating 120 of one or more embodiments may be described as abrasion resistant as measured by various methods, after being abraded according to a Taber Test after at least about 500 cycles. Various forms of abrasion test are known in the art, such as the test method specified in ASTM D1044-99, using abrasive media supplied by Taber Industries. Modified abrasion methods related to ASTM D1044-99 can be created using different types of abrading media, abradant geometry and motion, pressure, etc. in order to provide repeatable and measurable abrasion or wear tracks to meaningfully differentiate the abrasion resistance of different samples. For example, different test conditions will usually be appropriate for soft plastics vs. hard inorganic test samples. The embodiments described herein were subjected to a Taber Test, as defined herein, which is a specific modified version of ASTM D1044-99 that gives clear and repeatable differentiation of durability between different samples which comprise primarily hard inorganic materials, such as oxide glasses and oxide or nitride coatings. As used herein, the phrase “Taber Test” refers to a test method using a Taber Linear Abraser 5750 (TLA 5750) and accessories supplied by Taber Industries, in an environment including a temperature of about 22° C.±3° C. and Relative Humidity of up to about 70%. The TLA 5750 includes a CS-17 abraser material having a 6.7 mm diameter abraser head. Each sample was abraded according to the Taber Test and the abrasive damage was evaluated using both Haze and Bidirectional Transmittance Distribution Function (CCBTDF) measurements, among other methods. In the Taber Test, the procedure for abrading each sample includes placing the TLA 5750 and a flat sample support on a rigid, flat surface and securing the TLA 5750 and the sample support to the surface. Before each sample is abraded under the Taber Test, the abraser is refaced using a new S-14 refacing strip adhered to glass. The abraser is subjected to 10 refacing cycles using a cycle speed of 25 cycles/minute and stroke length of 1 inch, with no additional weight added (i.e., a total weight of about 350 g is used during refacing, which is the combined weight of the spindle and collet holding the abraser). The procedure then includes operating the TLA 5750 to abrade the sample, where the sample is placed in the sample support in contact with the abraser head and supporting the weight applied to the abraser head, using a cycle speed of 25 cycles/minute, and a stroke length of 1 inch, and a weight such that the total weight applied to the sample is 850 g (i.e., a 500 g auxiliary weight is applied in addition to the 350 g combined weight of the spindle and collet). The procedure includes forming two wear tracks on each sample for repeatability, and abrading each sample for 500 cycle counts in each of the two wear tracks on each sample.

In one or more embodiments, the anti-reflective coating 120 of the article 100 is abraded according to the above Taber Test and the article exhibits a haze of about 10% of less, as measured on the abraded side using a hazemeter supplied by BYK Gardner under the trademark Haze-Gard Plus®, using an aperture over the source port, the aperture having a diameter of 8 mm.

The article 100 of one or more embodiments exhibits such abrasion resistance with and without any additional coatings (including the additional coating 140, which will be described herein). In some embodiments, the haze may be about 9% or less, about 8% or less, about 7% or less, about 6% or less, about 5% or less, about 4% or less, about 3% or less, about 2% or less, about 1% or less, about 0.5% or less or about 0.3% or less. In some specific embodiments, the article 100 exhibits a haze in the range from about 0.1% to about 10%, from about 0.1% to about 9%, from about 0.1% to about 8%, from about 0.1% to about 7%, from about 0.1% to about 6%, from about 0.1% to about 5%, from about 0.1% to about 4%, from about 0.1% to about 3%, from about 0.1% to about 2%, from about 0.1% to about 1%, 0.3% to about 10%, from about 0.5% to about 10%, from about 1% to about 10%, from about 2% to about 10%, from about 3% to about 10%, from about 4% to about 10%, from about 5% to about 10%, from about 6% to about 10%, from about 7% to about 10%, from about 1% to about 8%, from about 2% to about 6%, from about 3% to about 5%, and all ranges and sub-ranges therebetween.

Alternate methods for quantifying the abrasion resistance are also contemplated here. In one or more embodiments, article 100 abraded by the Taber Test on the anti-reflective coating 120 may exhibit an abrasion resistance as measured by atomic force microscopy (AFM) surface profiling, which may be carried out for example over an 80×80 micron area, or multiple 80×80 micron areas (to sample a larger portion of the abraded area) of the anti-reflective coating 120. From these AFM surface scans, surface roughness statistics such as RMS roughness, Ra roughness, and peak-to-valley surface height may be evaluated. In one or more embodiments, the article 100 (or specifically, the anti-reflective coating 120) may exhibit average surface roughness (Ra) values of about 50 nm or less, about 25 nm or less, about 12 nm or less, about 10 nm or less, or about 5 nm or less, after being abraded under the Taber Test described above.

In one or more embodiments, the article 100 may exhibit an abrasion resistance, after being abraded by the Taber Test as measured by a light scattering measurement. In one or more embodiments, the light scattering measurement includes a bi-directional reflectance distribution function (BRDF) or bi-directional transmittance distribution function (BTDF) measurement carried out using a Radiant Zemax IS-SA™ instrument. This instrument has the flexibility to measure light scattering using any input angle from normal to about 85 degrees incidence in reflection, and from normal to about 85 degrees incidence in transmission, while also capturing all scattered light output in either reflection or transmission into 2*Pi steradians (a full hemisphere in reflection or transmission). In one embodiment, the article 100 exhibits an abrasion resistance, as measured using BTDF at normal incidence and analyzing the transmitted scattered light at a selected angular range, for example from about 10° to about 80° degrees in polar angles and any angular range therein. The full azimuthal range of angles can be analyzed and integrated, or particular azimuthal angular slices can be selected, for example from about 0° and 90° azimuthally. In the case of linear abrasion, it may be desired to choose an azimuthal direction that is substantially orthogonal to the abrasion direction so as to increase signal-to-noise of the optical scattering measurement. In one or more embodiments, the article 100 may exhibit a scattered light intensity as measured at the anti-reflective coating 120, of about less than about 0.1, about 0.05 or less, about 0.03 or less, about 0.02 or less, about 0.01 or less, about 0.005 or less, or about 0.003 or less (in units of 1/steradian), when using the Radiant Zemax IS-SA tool in CCBTDF mode at normal incidence in transmission, with a 2 mm aperture and a monochrometer set to 600 nm wavelength, and when evaluated at polar scattering angles in the range from about 15° to about 60° (e.g. specifically, about 20° or about 40°). Normal incidence in transmission may be otherwise known as zero degrees in transmission, which may be denoted as 180° incidence by the instrument software. In one or more embodiments, the scattered light intensity may be measured along an azimuthal direction substantially orthogonal to the abraded direction of a sample abraded by the Taber Test. In one example, the Taber Test may use from about 10 cycles to about 1000 cycles, and all values in between. These optical intensity values may also correspond to less than about 1%, less than about 0.5%, less than about 0.2%, or less than about 0.1% of the input light intensity that is scattered into polar scattering angles greater than about 5 degrees, greater than about 10 degrees, greater than about 30 degrees, or greater than about 45 degrees.

Generally speaking, BTDF testing at normal incidence, as described herein, is closely related to the transmission haze measurement, in that both are measuring the amount of light that is scattered in transmission through a sample (or, in this case the article 100, after abrading the anti-reflective coating 120). BTDF measurements provide more sensitivity as well as more detailed angular information, compared to haze measurements. BTDF allows measurement of scattering into different polar and azimuthal angles, for example allowing us to selectively evaluate the scattering into azimuthal angles that are substantially orthogonal to the abrasion direction in the linear Taber test (these are the angles where light scattering from linear abrasion is the highest). Transmission haze is essentially the integration of all scattered light measured by normal incidence BTDF into the entire hemisphere of polar angles greater than about +/−2.5 degrees.

The anti-reflective coating 120 and the article 100 may be described in terms of a hardness measured by a Berkovich Indenter Hardness Test. As used herein, the “Berkovich Indenter Hardness Test” includes measuring the hardness of a material on a surface thereof by indenting the surface with a diamond Berkovich indenter. The Berkovich Indenter Hardness Test includes indenting the anti-reflective surface 122 of the article or the surface of the anti-reflective coating 120 (or the surface of any one or more of the layers in the anti-reflective coating) with the diamond Berkovich indenter to form an indent to an indentation depth in the range from about 50 nm to about 1000 nm (or the entire thickness of the anti-reflective coating or layer, whichever is less) and measuring the maximum hardness from this indentation along the entire indentation depth range or a segment of this indentation depth (e.g., in the range from about 100 nm to about 600 nm), generally using the methods set forth in Oliver, W. C.; Pharr, G. M. An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments. J. Mater. Res., Vol. 7, No. 6, 1992, 1564-1583; and Oliver, W. C.; Pharr, G. M. Measurement of Hardness and Elastic Modulus by Instrument Indentation: Advances in Understanding and Refinements to Methodology. J. Mater. Res., Vol. 19, No. 1, 2004, 3-20. As used herein, hardness refers to a maximum hardness, and not an average hardness.

Typically, in nanoindentation measurement methods (such as by using a Berkovich indenter) of a coating that is harder than the underlying substrate, the measured hardness may appear to increase initially due to development of the plastic zone at shallow indentation depths and then increases and reaches a maximum value or plateau at deeper indentation depths. Thereafter, hardness begins to decrease at even deeper indentation depths due to the effect of the underlying substrate. Where a substrate having an increased hardness compared to the coating is utilized, the same effect can be seen; however, the hardness increases at deeper indentation depths due to the effect of the underlying substrate.

The indentation depth range and the hardness values at certain indentation depth range(s) can be selected to identify a particular hardness response of the optical film structures and layers thereof, described herein, without the effect of the underlying substrate. When measuring hardness of the optical film structure (when disposed on a substrate) with a Berkovich indenter, the region of permanent deformation (plastic zone) of a material is associated with the hardness of the material. During indentation, an elastic stress field extends well beyond this region of permanent deformation. As indentation depth increases, the apparent hardness and modulus are influenced by stress field interactions with the underlying substrate. The substrate influence on hardness occurs at deeper indentation depths (i.e., typically at depths greater than about 10% of the optical film structure or layer thickness). Moreover, a further complication is that the hardness response requires a certain minimum load to develop full plasticity during the indentation process. Prior to that certain minimum load, the hardness shows a generally increasing trend.

At small indentation depths (which also may be characterized as small loads) (e.g., up to about 50 nm), the apparent hardness of a material appears to increase dramatically versus indentation depth. This small indentation depth regime does not represent a true metric of hardness but instead, reflects the development of the aforementioned plastic zone, which is related to the finite radius of curvature of the indenter. At intermediate indentation depths, the apparent hardness approaches maximum levels. At deeper indentation depths, the influence of the substrate becomes more pronounced as the indentation depths increase. Hardness may begin to drop dramatically once the indentation depth exceeds about 30% of the optical film structure thickness or the layer thickness.

FIG. 40 illustrates the changes in measured hardness value as a function of indentation depth and thickness of a coating. As shown in FIG. 40, the hardness measured at intermediate indentation depths (at which hardness approaches and is maintained at maximum levels) and at deeper indentation depths depends on the thickness of a material or layer. FIG. 40 illustrates the hardness response of four different layers of AlO_(x)N_(y) having different thicknesses. The hardness of each layer was measured using the Berkovich Indenter Hardness Test. The 500 nm-thick layer exhibited its maximum hardness at indentation depths from about 100 nm to 180 nm, followed by a dramatic decrease in hardness at indentation depths from about 180 nm to about 200 nm, indicating the hardness of the substrate influencing the hardness measurement. The 1000 nm-thick layer exhibited a maximum hardness at indentation depths from about 100 nm to about 300 nm, followed by a dramatic decrease in hardness at indentation depths greater than about 300 nm. The 1500 nm-thick layer exhibited a maximum hardness at indentation depths from about 100 nm to about 550 nm and the 2000-nm thick layer exhibited a maximum hardness at indentation depths from about 100 nm to about 600 nm. Although FIG. 40 illustrates a thick single layer, the same behavior is observed in thinner coatings and those including multiple layers such as the anti-reflective coating 120 of the embodiments described herein.

In some embodiments, the anti-reflective coating 120 may exhibit a hardness of greater than about 5 GPa, as measured on the anti-reflective surface 122, by a Berkovitch Indenter Hardness Test. The antireflective coating 120 may exhibit a hardness of about 8 GPa or greater, about 10 GPa or greater or about 12 GPa or greater. The article 100, including the anti-reflective coating 120 and any additional coatings, as described herein, may exhibit a hardness of about 5 GPa or greater, about 8 GPa or greater, about 10 GPa or greater or about 12 GPa or greater, as measured on the anti-reflective surface 122, by a Berkovitch Indenter Hardness Test. Such measured hardness values may be exhibited by the anti-reflective coating 120 and/or the article 100 along an indentation depth of about 50 nm or greater or about 100 nm or greater (e.g., from about 100 nm to about 300 nm, from about 100 nm to about 400 nm, from about 100 nm to about 500 nm, from about 100 nm to about 600 nm, from about 200 nm to about 300 nm, from about 200 nm to about 400 nm, from about 200 nm to about 500 nm, or from about 200 nm to about 600 nm).

The anti-reflective coating 120 may have at least one layer having a hardness (as measured on the surface of such layer, e.g., surface of the second high RI layer 130B of FIG. 2) of about 12 GPa or greater, about 13 GPa or greater, about 14 GPa or greater, about 15 GPa or greater, about 16 GPa or greater, about 17 GPa or greater, about 18 GPa or greater, about 19 GPa or greater, about 20 GPa or greater, about 22 GPa or greater, about 23 GPa or greater, about 24 GPa or greater, about 25 GPa or greater, about 26 GPa or greater, or about 27 GPa or greater (up to about 50 GPa), as measured by the Berkovich Indenter Hardness Test. The hardness of such layer may be in the range from about 18 GPa to about 21 GPa, as measured by the Berkovich Indenter Hardness Test. Such measured hardness values may be exhibited by the at least one layer along an indentation depth of about 50 nm or greater or 100 nm or greater (e.g., from about 100 nm to about 300 nm, from about 100 nm to about 400 nm, from about 100 nm to about 500 nm, from about 100 nm to about 600 nm, from about 200 nm to about 300 nm, from about 200 nm to about 400 nm, from about 200 nm to about 500 nm, or from about 200 nm to about 600 nm). In one or more embodiments, the article exhibits a hardness that is greater than the hardness of the substrate (which can be measured on the opposite surface from the anti-reflective surface).

In one or more embodiments, the anti-reflective coating 120 or individual layers within the anti-reflective coating may exhibit an elastic modulus of about 75 GPa or greater, about 80 GPa or greater or about 85 GPa or greater, as measured on the anti-reflective surface 122, by indenting that surface with a Berkovitch indenter. These modulus values may represent a modulus measured very close to the anti-reflective surface 122, e.g. at indentation depths of 0-50 nm, or it may represent a modulus measured at deeper indentation depths, e.g. from about 50-1000 nm.

Optical interference between reflected waves from the anti-reflective coating 120/air interface and the anti-reflective coating 120/substrate 110 interface can lead to spectral reflectance and/or transmittance oscillations that create apparent color in the article 100. As used herein, the term “transmittance” is defined as the percentage of incident optical power within a given wavelength range transmitted through a material (e.g., the article, the substrate or the optical film or portions thereof). The term “reflectance” is similarly defined as the percentage of incident optical power within a given wavelength range that is reflected from a material (e.g., the article, the substrate, or the optical film or portions thereof). Transmittance and reflectance are measured using a specific linewidth. In one or more embodiments, the spectral resolution of the characterization of the transmittance and reflectance is less than 5 nm or 0.02 eV. The color may be more pronounced in reflection. The angular color shifts in reflection with viewing angle due to a shift in the spectral reflectance oscillations with incident illumination angle. Angular color shifts in transmittance with viewing angle are also due to the same shift in the spectral transmittance oscillation with incident illumination angle. The observed color and angular color shifts with incident illumination angle are often distracting or objectionable to device users, particularly under illumination with sharp spectral features such as fluorescent lighting and some LED lighting. Angular color shifts in transmission may also play a factor in angular color shift in reflection and vice versa. Factors in angular color shifts in transmission and/or reflection may also include angular color shifts due to viewing angle or color shifts away from a certain white point that may be caused by material absorption (somewhat independent of angle) defined by a particular illuminant or test system.

The oscillations may be described in terms of amplitude. As used herein, the term “amplitude” includes the peak-to-valley change in reflectance or transmittance.

The phrase “average amplitude” includes the peak-to-valley change in reflectance or transmittance averaged within the optical wavelength regime. As used herein, the “optical wavelength regime” includes the wavelength range from about 400 nm to about 800 nm (and more specifically from about 450 nm to about 650 nm).

The embodiments of this disclosure include an anti-reflective coating to provide improved optical performance, in terms of colorlessness and/or smaller angular color shifts with viewed at varying incident illumination angles from normal incidence under different illuminants.

One aspect of this disclosure pertains to an article that exhibits colorlessness in reflectance and/or transmittance even when viewed at different incident illumination angles under an illuminant. In one or more embodiments, the article exhibits an angular color shift in reflectance and/or transmittance of about 5 or less or about 2 or less between a reference illumination angle and any incidental illumination angles, in the ranges provided herein. As used herein, the phrase “color shift” (angular or reference point) refers to the change in both a* and b*, under the CIE L*, a*, b* colorimetry system in reflectance and/or transmittance. It should be understood that unless otherwise noted, the L* coordinate of the articles described herein are the same at any angle or reference point and do not influence color shift. For example, angular color shift may be determined using the following Equation (1):

√((a* ₂ −a* ₁)²+(b* ₂ −b* ₁)²)  (1)

with a*₁, and b*₁ representing the a* and b* coordinates of the article when viewed at a reference illumination angle (which may include normal incidence) and a*₂, and b*₂ representing the a* and b* coordinates of the article when viewed at an incident illumination angle, provided that the incident illumination angle is different from reference illumination angle and in some cases differs from the reference illumination angle by at least about 1 degree, 2 degrees or about 5 degrees. In some instances, an angular color shift in reflectance and/or transmittance of about 10 or less (e.g., 5 or less, 4 or less, 3 or less, or 2 or less) is exhibited by the article when viewed at various incident illumination angles from a reference illumination angle, under an illuminant. In some instances the angular color shift in reflectance and/or transmittance is about 1.9 or less, 1.8 or less, 1.7 or less, 1.6 or less, 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, 1.1 or less, 1 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less. In some embodiments, the angular color shift may be about 0. The illuminant can include standard illuminants as determined by the CIE, including A illuminants (representing tungsten-filament lighting), B illuminants (daylight simulating illuminants), C illuminants (daylight simulating illuminants), D series illuminants (representing natural daylight), and F series illuminants (representing various types of fluorescent lighting). In specific examples, the articles exhibit an angular color shift in reflectance and/or transmittance of about 2 or less when viewed at incident illumination angle from the reference illumination angle under a CIE F2, F10, F11, F12 or D65 illuminant or more specifically under a CIE F2 illuminan.

The reference illumination angle may include normal incidence (i.e., 0 degrees), or 5 degrees from normal incidence, 10 degrees from normal incidence, 15 degrees from normal incidence, 20 degrees from normal incidence, 25 degrees from normal incidence, 30 degrees from normal incidence, 35 degrees from normal incidence, 40 degrees from normal incidence, 50 degrees from normal incidence, 55 degrees from normal incidence, or 60 degrees from normal incidence, provided the difference between the reference illumination angle and the difference between the incident illumination angle and the reference illumination angle is at least about 1 degree, 2 degrees or about 5 degrees. The incident illumination angle may be, with respect to the reference illumination angle, in the range from about 5 degrees to about 80 degrees, from about 5 degrees to about 80 degrees, from about 5 degrees to about 70 degrees, from about 5 degrees to about 65 degrees, from about 5 degrees to about 60 degrees, from about 5 degrees to about 55 degrees, from about 5 degrees to about 50 degrees, from about 5 degrees to about 45 degrees, from about 5 degrees to about 40 degrees, from about 5 degrees to about 35 degrees, from about 5 degrees to about 30 degrees, from about 5 degrees to about 25 degrees, from about 5 degrees to about 20 degrees, from about 5 degrees to about 15 degrees, and all ranges and sub-ranges therebetween, away from normal incidence. The article may exhibit the angular color shifts in reflectance and/or transmittance described herein at and along all the incident illumination angles in the range from about 2 degrees to about 80 degrees, when the reference illumination angle is normal incidence. In some embodiments, the article may exhibit the angular color shifts in reflectance and/or transmittance described herein at and along all the incident illumination angles in the range from about 2 degrees to about 80 degrees, when the difference between the incident illumination angle and the reference illumination angle is at least about 1 degree, 2 degrees or about 5 degrees. In one example, the article may exhibit an angular color shift in reflectance and/or transmittance of 2 or less at any incident illumination angle in the range from about 2 degrees to about 60 degrees, from about 5 degrees to about 60 degrees, or from about 10 degrees to about 60 degrees away from a reference illumination angle equal to normal incidence. In other examples, the article may exhibit an angular color shift in reflectance and/or transmittance of 2 or less when the reference illumination angle is 10 degrees and the incident illumination angle is any angle in the range from about 12 degrees to about 60 degrees, from about 15 degrees to about 60 degrees, or from about 20 degrees to about 60 degrees away from the reference illumination angle.

In some embodiments, the angular color shift may be measured at all angles between a reference illumination angle (e.g., normal incidence) and an incident illumination angle in the range from about 20 degrees to about 80 degrees. In other words, the angular color shift may be measured and may be less than about 5 or less than about 2, at all angles in the range from about 0 degrees and 20 degrees, from about 0 degrees to about 30 degrees, from about 0 degrees to about 40 degrees, from about 0 degrees to about 50 degrees, from about 0 degrees to about 60 degrees or from about 0 degrees to about 80 degrees.

In one or more embodiments, the article exhibits a color in the CIE L*, a*, b* colorimetry system in reflectance and/or transmittance such that the distance or reference point color shift between the transmittance color or reflectance coordinates from a reference point is less than about 5 or less than about 2 under an illumaint (which can include standard illuminants as determined by the CIE, including A illuminants (representing tungsten-filament lighting), B illuminants (daylight simulating illuminants), C illuminants (daylight simulating illuminants), D series illuminants (representing natural daylight), and F series illuminants (representing various types of fluorescent lighting)). In specific examples, the articles exhibit a color shift in reflectance and/or transmittance of about 2 or less when viewed at incident illumination angle from the reference illumination angle under a CIE F2, F10, F11, F12 or D65 illuminant or more specifically under a CIE F2 illuminant. Stated another way, the article may exhibit a transmittance color (or transmittance color coordinates) and/or a reflectance color (or reflectance color coordinates) measured at the anti-reflective surface 122 having a reference point color shift of less than about 2 from a reference point, as defined herein. Unless otherwise noted, the transmittance color or transmittance color coordinates are measured on two surfaces of the article including at the anti-reflective surface 122 and the opposite bare surface of the article (i.e., 114). Unless otherwise noted, the reflectance color or reflectance color coordinates are measured on only the anti-reflective surface 122 of the article.

In one or more embodiments, the reference point may be the origin (0, 0) in the CIE L*, a*, b* colorimetry system (or the color coordinates a*=0, b*=0), color coordinates (−2, −2) or the transmittance or reflectance color coordinates of the substrate. It should be understood that unless otherwise noted, the L* coordinate of the articles described herein are the same as the reference point and do not influence color shift. Where the reference point color shift of the article is defined with respect to the substrate, the transmittance color coordinates of the article are compared to the transmittance color coordinates of the substrate and the reflectance color coordinates of the article are compared to the reflectance color coordinates of the substrate.

In one or more specific embodiments, the reference point color shift of the transmittance color and/or the reflectance color may be less than 1 or even less than 0.5. In one or more specific embodiments, the reference point color shift for the transmittance color and/or the reflectance color may be 1.8, 1.6, 1.4, 1.2, 0.8, 0.6, 0.4, 0.2, 0 and all ranges and sub-ranges therebetween. Where the reference point is the color coordinates a*=0, b*=0, the reference point color shift is calculated by Equation (2).

reference point color shift=√((a* _(article))²+(b* _(article))²)  (2)

Where the reference point is the color coordinates a*=−2, b*=−2, the reference point color shift is calculated by Equation (3).

reference point color shift=√((a* _(article)+2)²+(b* _(article)+2)²)  (3)

Where the reference point is the color coordinates of the substrate, the reference point color shift is calculated by Equation (4).

reference point color shift=√((a* _(article) −a* _(substrate))²+(b* _(article) −b* _(substrate))²)  (4)

In some embodiments, the article may exhibit a transmittance color (or transmittance color coordinates) and a reflectance color (or reflectance color coordinates) such that the reference point color shift is less than 2 when the reference point is any one of the color coordinates of the substrate, the color coordinates a*=0, b*=0 and the coordinates a*=−2, b*=−2.

In one or more embodiment, the article may exhibit a b* value in reflectance (as measured at the anti-reflective surface only) in the range from about −5 to about 1, from about −5 to about 0, from about −4 to about 1, or from about −4 to about 0, in the CIE L*, a*, b* colorimetry system at all incidence illumination angles in the range from about 0 to about 60 degrees (or from about 0 degrees to about 40 degrees or from about 0 degrees to about 30 degrees).

In one or more embodiment, the article may exhibit a b* value in transmittance (as measured at the anti-reflective surface and the opposite bare surface of the article) in the range from about −2 to about 2, from about −1 to about 2, from about −0.5 to about 2, from about 0 to about 2, from about 0 to about 1, from about −2 to about 0.5, from about −2 to about 1, from about −1 to about 1, or from about 0 to about 0.5, in the CIE L*, a*, b* colorimetry system at all incidence illumination angles in the range from about 0 to about 60 degrees (or from about 0 degrees to about 40 degrees or from about 0 degrees to about 30 degrees).

In some embodiments, the article exhibits an a* value in transmittance (at the anti-reflective surface and the opposite bare surface) in the range from about −1.5 to about 1.5 (e.g., −1.5 to −1.2, −1.5 to −1, −1.2 to 1.2, −1 to 1, −1 to 0.5, or −1 to 0) at incident illumination angles in the range from about 0 degrees to about 60 degrees under illuminants D65, A, and F2. In some embodiments, the article exhibits a b* value in transmittance (at the anti-reflective surface and the opposite bare surface) in the range from about −1.5 to about 1.5 (e.g., −1.5 to −1.2, −1.5 to −1, −1.2 to 1.2, −1 to 1, −1 to 0.5, or −1 to 0) at incident illumination angles in the range from about 0 degrees to about 60 degrees under illuminants D65, A, and F2.

In some embodiments, the article exhibits an a* value in reflectance (at only the anti-reflective surface) in the range from about −5 to about 2 (e.g., −4.5 to 1.5, −3 to 0, −2.5 to 0.25) at incident illumination angles in the range from about 0 degrees to about 60 degrees under illuminants D65, A, and F2. In some embodiments, the article exhibits a b* value in reflectance (at only the anti-reflective surface) in the range from about −7 to about −1.5 at incident illumination angles in the range from about 0 degrees to about 60 degrees under illuminants D65, A, and F2.

The article of one or more embodiments, or the anti-reflective surface 122 of one or more articles, may exhibit an average light transmittance of about 95% or greater (e.g., about 9.5% or greater, about 96% or greater, about 96.5% or greater, about 97% or greater, about 97.5% or greater, about 98% or greater, about 98.5% or greater or about 99% or greater) over the optical wavelength regime in the range from about 400 nm to about 800 nm. In some embodiments, the article, or the anti-reflective surface 122 of one or more articles, may exhibit an average light reflectance of about 2% or less (e.g., about 1.5% or less, about 1% or less, about 0.75% or less, about 0.5% or less, or about 0.25% or less) over the optical wavelength regime in the range from about 400 nm to about 800 nm. These light transmittance and light reflectance values may be observed over the entire optical wavelength regime or over selected ranges of the optical wavelength regime (e.g., a 100 nm wavelength range, 150 nm wavelength range, a 200 nm wavelength range, a 250 nm wavelength range, a 280 nm wavelength range, or a 300 nm wavelength range, within the optical wavelength regime). In some embodiments, these light reflectance and transmittance values may be a total reflectance or total transmittance (taking into account reflectance or transmittance on both the anti-reflective surface 122 and the opposite major surfaces, 114). Unless otherwise specified, the average reflectance or transmittance is measured at an incident illumination angle of 0 degrees (however, such measurements may be provided at incident illumination angles of 45 degrees or 60 degrees).

In some embodiments, the article of one or more embodiments, or the anti-reflective surface 122 of one or more articles, may exhibit an average visible photopic reflectance of about 1% or less, about 0.7% or less, about 0.5% or less, or about 0.45% or less over the optical wavelength regime. These photopic reflectance values may be exhibited at incident illumination angles in the range from about 0° to about 20°, from about 0° to about 40° or from about 0° to about 60°. As used herein, photopic reflectance mimics the response of the human eye by weighting the reflectance versus wavelength spectrum according to the human eye's sensitivity. Photopic reflectance may also be defined as the luminance, or tristimulus Y value of reflected light, according to known conventions such as CIE color space conventions. The average photopic reflectance is defined in Equation (5) as the spectral reflectance, R(λ) multiplied by the illuminant spectrum, I(λ) and the CIE's color matching function y(λ), related to the eye's spectral response:

$\left\langle R_{p} \right\rangle = {\int\limits_{380\mspace{14mu} n\; m}^{720\mspace{14mu} n\; m}{{R(\lambda)} \times {I(\lambda)} \times {\overset{\_}{y}(\lambda)}d\lambda}}$

(5)

In a specific embodiment, the anti-reflective surface 122 of one or more articles (i.e. when measuring the anti-reflective surface 122 only through a single-sided measurement), may exhibit an average visible photopic reflectance of about 2% or less, 1.8% or less, 1.5% or less, 1.2% or less, 1% or less, 0.9% or less, 0.7% or less, about 0.5% or less, about 0.45% or less, about 0.4% or less, or about 0.35% or less. In some cases, the average visible photopic reflectance ranges are exhibited while simultaneously exhibiting a maximum reflectance color shift, over the entire incident illumination angle range from about 5 degrees to about 60 degrees (with the reference illumination angle being normal incidence) using D65 illumination, of less than about 5.0, less than about 4.0, less than about 3.0, less than about 2.0, less than about 1.5, or less than about 1.25. These maximum reflectance color shift values represent the lowest color point value measured at any angle from about 5 degrees to about 60 degrees from normal incidence, subtracted from the highest color point value measured at any angle in the same range. The values may represent a maximum change in a* value (a*_(highest)−a*_(lowest)), a maximum change in b* value (b*_(highest)−b*_(lowest)), a maximum change in both a* and b* values, or a maximum change in the quantity √((a*_(highest)−a*lowest)+(b*_(highest)−b*_(lowest))).

In one or more embodiments, the article may exhibit a reflectance spectra, measured at the anti-reflective surface only, at or near normal incidence (e.g., from about 0 to about 10 degrees or from about 0 degrees to about 6 degrees) that can be characterized in terms of the following features: a maximum reflectance and a minimum reflectance over the wavelength range from about 400 nm to about 480 nm (the maximum reflectance over this range is referred to as R400-max and the minimum reflectance over this range is referred to as R400-min), a maximum reflectance and a minimum reflectance over the wavelength range from about 500 nm to about 600 nm (the maximum reflectance over this range is referred to as R500-max and the minimum reflectance over this range is referred to as R500-min, respectively), and a maximum reflectance and a minimum reflectance in the wavelength range from about 640 nm to about 710 nm (the maximum reflectance over the wavelength range from about 640 nm to about 710 nm is referred to as R640-max the minimum reflectance over the wavelength range from about 640 nm to about 710 nm is referred to as R640-min). In some embodiments, the reflectance spectra exhibit any one or more of: R400-max is greater than R500-max, R400-max is greater than R640-max, R400-min is less than R500-min; R600-min is less than R500-min. In some embodiments, the reflectance spectra exhibits any one or more of R400-max in in the range from about 0.6% to about 1.5%, R400-min is in the range from about 0% to about 0.3%, R500-max is in the range of from about 0.5% to about 0.9%, R500-min is in the range from about 0.3% to about 0.7%, R640-max is in the range from about 0.5% to about 0.9% and R640-min is in the range from about 0 to 0.3%.

Substrate

The substrate 110 may include an inorganic material and may include an amorphous substrate, a crystalline substrate or a combination thereof. The substrate 110 may be formed from man-made materials and/or naturally occurring materials (e.g., quartz and polymers). For example, in some instances, the substrate 110 may be characterized as organic and may specifically be polymeric. Examples of suitable polymers include, without limitation: thermoplastics including polystyrene (PS) (including styrene copolymers and blends), polycarbonate (PC) (including copolymers and blends), polyesters (including copolymers and blends, including polyethyleneterephthalate and polyethyleneterephthalate copolymers), polyolefins (PO) and cyclicpolyolefins (cyclic-PO), polyvinylchloride (PVC), acrylic polymers including polymethyl methacrylate (PMMA) (including copolymers and blends), thermoplastic urethanes (TPU), polyetherimide (PEI) and blends of these polymers with each other. Other exemplary polymers include epoxy, styrenic, phenolic, melamine, and silicone resins.

In some specific embodiments, the substrate 110 may specifically exclude polymeric, plastic and/or metal substrates. The substrate may be characterized as alkali-including substrates (i.e., the substrate includes one or more alkalis). In one or more embodiments, the substrate exhibits a refractive index in the range from about 1.45 to about 1.55. In specific embodiments, the substrate 110 may exhibit an average strain-to-failure at a surface on one or more opposing major surface that is 0.5% or greater, 0.6% or greater, 0.7% or greater, 0.8% or greater, 0.9% or greater, 1% or greater, 1.1% or greater, 1.2% or greater, 1.3% or greater, 1.4% or greater 1.5% or greater or even 2% or greater, as measured using ball-on-ring testing using at least 5, at least 10, at least 15, or at least 20 samples. In specific embodiments, the substrate 110 may exhibit an average strain-to-failure at its surface on one or more opposing major surface of about 1.2%, about 1.4%, about 1.6%, about 1.8%, about 2.2%, about 2.4%, about 2.6%, about 2.8%, or about 3% or greater.

Suitable substrates 110 may exhibit an elastic modulus (or Young's modulus) in the range from about 30 GPa to about 120 GPa. In some instances, the elastic modulus of the substrate may be in the range from about 30 GPa to about 110 GPa, from about 30 GPa to about 100 GPa, from about 30 GPa to about 90 GPa, from about 30 GPa to about 80 GPa, from about 30 GPa to about 70 GPa, from about 40 GPa to about 120 GPa, from about 50 GPa to about 120 GPa, from about 60 GPa to about 120 GPa, from about 70 GPa to about 120 GPa, and all ranges and sub-ranges therebetween.

In one or more embodiments, the amorphous substrate may include glass, which may be strengthened or non-strengthened. Examples of suitable glass include soda lime glass, alkali aluminosilicate glass, alkali containing borosilicate glass and alkali aluminoborosilicate glass. In some variants, the glass may be free of lithia. In one or more alternative embodiments, the substrate 110 may include crystalline substrates such as glass ceramic substrates (which may be strengthened or non-strengthened) or may include a single crystal structure, such as sapphire. In one or more specific embodiments, the substrate 110 includes an amorphous base (e.g., glass) and a crystalline cladding (e.g., sapphire layer, a polycrystalline alumina layer and/or or a spinel (MgAl₂O₄) layer).

The substrate 110 may be substantially planar or sheet-like, although other embodiments may utilize a curved or otherwise shaped or sculpted substrate. The substrate 110 may be substantially optically clear, transparent and free from light scattering. In such embodiments, the substrate may exhibit an average light transmission over the optical wavelength regime of about 85% or greater, about 86% or greater, about 87% or greater, about 88% or greater, about 89% or greater, about 90% or greater, about 91% or greater or about 92% or greater. In one or more alternative embodiments, the substrate 110 may be opaque or exhibit an average light transmission over the optical wavelength regime of less than about 10%, less than about 9%, less than about 8%, less than about 7%, less than about 6%, less than about 5%, less than about 4%, less than about 3%, less than about 2%, less than about 1%, or less than about 0%. In some embodiments, these light reflectance and transmittance values may be a total reflectance or total transmittance (taking into account reflectance or transmittance on both major surfaces of the substrate) or may be observed on a single side of the substrate (i.e., on the anti-reflective surface 122 only, without taking into account the opposite surface). Unless otherwise specified, the average reflectance or transmittance is measured at an incident illumination angle of 0 degrees (however, such measurements may be provided at incident illumination angles of 45 degrees or 60 degrees). The substrate 110 may optionally exhibit a color, such as white, black, red, blue, green, yellow, orange etc.

Additionally or alternatively, the physical thickness of the substrate 110 may vary along one or more of its dimensions for aesthetic and/or functional reasons. For example, the edges of the substrate 110 may be thicker as compared to more central regions of the substrate 110. The length, width and physical thickness dimensions of the substrate 110 may also vary according to the application or use of the article 100.

The substrate 110 may be provided using a variety of different processes. For instance, where the substrate 110 includes an amorphous substrate such as glass, various forming methods can include float glass processes and down-draw processes such as fusion draw and slot draw.

Once formed, a substrate 110 may be strengthened to form a strengthened substrate. As used herein, the term “strengthened substrate” may refer to a substrate that has been chemically strengthened, for example through ion-exchange of larger ions for smaller ions in the surface of the substrate. However, other strengthening methods known in the art, such as thermal tempering, or utilizing a mismatch of the coefficient of thermal expansion between portions of the substrate to create compressive stress and central tension regions, may be utilized to form strengthened substrates.

Where the substrate is chemically strengthened by an ion exchange process, the ions in the surface layer of the substrate are replaced by—or exchanged with—larger ions having the same valence or oxidation state. Ion exchange processes are typically carried out by immersing a substrate in a molten salt bath containing the larger ions to be exchanged with the smaller ions in the substrate. It will be appreciated by those skilled in the art that parameters for the ion exchange process, including, but not limited to, bath composition and temperature, immersion time, the number of immersions of the substrate in a salt bath (or baths), use of multiple salt baths, additional steps such as annealing, washing, and the like, are generally determined by the composition of the substrate and the desired compressive stress (CS), depth of compressive stress layer (or depth of layer) of the substrate that result from the strengthening operation. By way of example, ion exchange of alkali metal-containing glass substrates may be achieved by immersion in at least one molten bath containing a salt such as, but not limited to, nitrates, sulfates, and chlorides of the larger alkali metal ion. The temperature of the molten salt bath typically is in a range from about 380° C. up to about 450° C., while immersion times range from about 15 minutes up to about 40 hours. However, temperatures and immersion times different from those described above may also be used.

In addition, non-limiting examples of ion exchange processes in which glass substrates are immersed in multiple ion exchange baths, with washing and/or annealing steps between immersions, are described in U.S. patent application Ser. No. 12/500,650, filed Jul. 10, 2009, by Douglas C. Allan et al., entitled “Glass with Compressive Surface for Consumer Applications” and claiming priority from U.S. Provisional Patent Application No. 61/079,995, filed Jul. 11, 2008, in which glass substrates are strengthened by immersion in multiple, successive, ion exchange treatments in salt baths of different concentrations; and U.S. Pat. No. 8,312,739, by Christopher M. Lee et al., issued on Nov. 20, 2012, and entitled “Dual Stage Ion Exchange for Chemical Strengthening of Glass,” and claiming priority from U.S. Provisional Patent Application No. 61/084,398, filed Jul. 29, 2008, in which glass substrates are strengthened by ion exchange in a first bath is diluted with an effluent ion, followed by immersion in a second bath having a smaller concentration of the effluent ion than the first bath. The contents of U.S. patent application Ser. No. 12/500,650 and U.S. Pat. No. 8,312,739 are incorporated herein by reference in their entirety.

The degree of chemical strengthening achieved by ion exchange may be quantified based on the parameters of central tension (CT), surface CS, and depth of layer (DOL). Surface CS may be measured near the surface or within the strengthened glass at various depths. A maximum CS value may include the measured CS at the surface (CS_(s)) of the strengthened substrate. The CT, which is computed for the inner region adjacent the compressive stress layer within a glass substrate, can be calculated from the CS, the physical thickness t, and the DOL. CS and DOL are measured using those means known in the art. Such means include, but are not limited to, measurement of surface stress (FSM) using commercially available instruments such as the FSM-6000, manufactured by Luceo Co., Ltd. (Tokyo, Japan), or the like, and methods of measuring CS and DOL are described in ASTM 1422C-99, entitled “Standard Specification for Chemically Strengthened Flat Glass,” and ASTM 1279.19779 “Standard Test Method for Non-Destructive Photoelastic Measurement of Edge and Surface Stresses in Annealed, Heat-Strengthened, and Fully-Tempered Flat Glass,” the contents of which are incorporated herein by reference in their entirety. Surface stress measurements rely upon the accurate measurement of the stress optical coefficient (SOC), which is related to the birefringence of the glass substrate. SOC in turn is measured by those methods that are known in the art, such as fiber and four point bend methods, both of which are described in ASTM standard C770-98 (2008), entitled “Standard Test Method for Measurement of Glass Stress-Optical Coefficient,” the contents of which are incorporated herein by reference in their entirety, and a bulk cylinder method. The relationship between CS and CT is given by the expression (1):

CT=(CS·DOL)/(t−2 DOL)  (1),

wherein t is the physical thickness (μm) of the glass article. In various sections of the disclosure, CT and CS are expressed herein in megaPascals (MPa), physical thickness t is expressed in either micrometers (μm) or millimeters (mm) and DOL is expressed in micrometers (μm).

In one embodiment, a strengthened substrate 110 can have a surface CS of 250 MPa or greater, 300 MPa or greater, e.g., 400 MPa or greater, 450 MPa or greater, 500 MPa or greater, 550 MPa or greater, 600 MPa or greater, 650 MPa or greater, 700 MPa or greater, 750 MPa or greater or 800 MPa or greater. The strengthened substrate may have a DOL of 10 μm or greater, 15 μm or greater, 20 μm or greater (e.g., 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm or greater) and/or a CT of 10 MPa or greater, 20 MPa or greater, 30 MPa or greater, 40 MPa or greater (e.g., 42 MPa, 45 MPa, or 50 MPa or greater) but less than 100 MPa (e.g., 95, 90, 85, 80, 75, 70, 65, 60, 55 MPa or less). In one or more specific embodiments, the strengthened substrate has one or more of the following: a surface CS greater than 500 MPa, a DOL greater than 15 μm, and a CT greater than 18 MPa.

Example glasses that may be used in the substrate may include alkali aluminosilicate glass compositions or alkali aluminoborosilicate glass compositions, though other glass compositions are contemplated. Such glass compositions are capable of being chemically strengthened by an ion exchange process. One example glass composition comprises SiO₂, B₂O₃ and Na₂O, where (SiO₂+B₂O₃)≥66 mol. %, and Na₂O≥9 mol. %. In an embodiment, the glass composition includes at least 6 wt. % aluminum oxide. In a further embodiment, the substrate includes a glass composition with one or more alkaline earth oxides, such that a content of alkaline earth oxides is at least 5 wt. %. Suitable glass compositions, in some embodiments, further comprise at least one of K₂O, MgO, and CaO. In a particular embodiment, the glass compositions used in the substrate can comprise 61-75 mol. % SiO2; 7-15 mol. % Al₂O₃; 0-12 mol. % B₂O₃; 9-21 mol. % Na₂O; 0-4 mol. % K₂O; 0-7 mol. % MgO; and 0-3 mol. % CaO.

A further example glass composition suitable for the substrate comprises: 60-70 mol. % SiO₂; 6-14 mol. % Al₂O₃; 0-15 mol. % B₂O₃; 0-15 mol. % Li₂O; 0-20 mol. % Na₂O; 0-10 mol. % K₂O; 0-8 mol. % MgO; 0-10 mol. % CaO; 0-5 mol. % ZrO₂; 0-1 mol. % SnO₂; 0-1 mol. % CeO₂; less than 50 ppm As₂O₃; and less than 50 ppm Sb₂O₃; where 12 mol. %≤(Li₂O+Na₂O+K₂O)≤20 mol. % and 0 mol. %≤(MgO+CaO)≤10 mol. %.

A still further example glass composition suitable for the substrate comprises: 63.5-66.5 mol. % SiO₂; 8-12 mol. % Al₂O₃; 0-3 mol. % B₂O₃; 0-5 mol. % Li₂O; 8-18 mol. % Na₂O; 0-5 mol. % K₂O; 1-7 mol. % MgO; 0-2.5 mol. % CaO; 0-3 mol. % ZrO₂; 0.05-0.25 mol. % SnO₂; 0.05-0.5 mol. % CeO₂; less than 50 ppm As₂O₃; and less than 50 ppm Sb₂O₃; where 14 mol. %≤(Li₂O+Na₂O+K₂O)≤18 mol. % and 2 mol. %≤(MgO+CaO)≤7 mol. %.

In a particular embodiment, an alkali aluminosilicate glass composition suitable for the substrate comprises alumina, at least one alkali metal and, in some embodiments, greater than 50 mol. % SiO₂, in other embodiments at least 58 mol. % SiO₂, and in still other embodiments at least 60 mol. % SiO₂, wherein the ratio (Al₂O₃+B₂O₃)/Σmodifiers (i.e., sum of modifiers) is greater than 1, where in the ratio the components are expressed in mol. % and the modifiers are alkali metal oxides. This glass composition, in particular embodiments, comprises: 58-72 mol. % SiO₂; 9-17 mol. % Al₂O₃; 2-12 mol. % B₂O₃; 8-16 mol. % Na₂O; and 0-4 mol. % K₂O, wherein the ratio (Al₂O₃+B₂O₃)/Σmodifiers (i.e., sum of modifiers) is greater than 1.

In still another embodiment, the substrate may include an alkali aluminosilicate glass composition comprising: 64-68 mol. % SiO₂; 12-16 mol. % Na₂O; 8-12 mol. % Al₂O₃; 0-3 mol. % B₂O₃; 2-5 mol. % K₂O; 4-6 mol. % MgO; and 0-5 mol. % CaO, wherein: 66 mol. %≤SiO₂+B₂O₃+CaO≤69 mol. %; Na₂O+K₂O+B₂O₃+MgO+CaO+SrO>10 mol. %; 5 mol. %≤MgO+CaO+SrO≤8 mol. %; (Na₂O+B₂O₃)—Al₂O₃≤2 mol. %; 2 mol. % Na₂O—Al₂O₃≤6 mol. %; and 4 mol. %≤(Na₂O+K₂O)—Al₂O₃≤10 mol. %.

In an alternative embodiment, the substrate may comprise an alkali aluminosilicate glass composition comprising: 2 mol % or more of Al₂O₃ and/or ZrO₂, or 4 mol % or more of Al₂O₃ and/or ZrO₂.

Where the substrate 110 includes a crystalline substrate, the substrate may include a single crystal, which may include Al₂O₃. Such single crystal substrates are referred to as sapphire. Other suitable materials for a crystalline substrate include polycrystalline alumina layer and/or spinel (MgAl₂O₄).

Optionally, the crystalline substrate 110 may include a glass ceramic substrate, which may be strengthened or non-strengthened. Examples of suitable glass ceramics may include Li₂O—Al₂O₃—SiO₂ system (i.e. LAS-System) glass ceramics, MgO—Al₂O₃—SiO₂ system (i.e. MAS-System) glass ceramics, and/or glass ceramics that include a predominant crystal phase including β-quartz solid solution, β-spodumene ss, cordierite, and lithium disilicate. The glass ceramic substrates may be strengthened using the chemical strengthening processes disclosed herein. In one or more embodiments, MAS-System glass ceramic substrates may be strengthened in Li₂SO₄ molten salt, whereby an exchange of 2Li⁺ for Mg²⁺ can occur.

The substrate 110 according to one or more embodiments can have a physical thickness ranging from about 100 μm to about 5 mm. Example substrate 110 physical thicknesses range from about 100 μm to about 500 μm (e.g., 100, 200, 300, 400 or 500 μm). Further example substrate 110 physical thicknesses range from about 500 μm to about 1000 μm (e.g., 500, 600, 700, 800, 900 or 1000 μm). The substrate 110 may have a physical thickness greater than about 1 mm (e.g., about 2, 3, 4, or 5 mm). In one or more specific embodiments, the substrate 110 may have a physical thickness of 2 mm or less or less than 1 mm. The substrate 110 may be acid polished or otherwise treated to remove or reduce the effect of surface flaws.

Anti-Reflective Coating

As shown in FIG. 1, the anti-reflective coating 120 may include a plurality of layers 120A, 120B, 120C. In some embodiments, one or more layers may be disposed on the opposite side of the substrate 110 from the anti-reflective coating 120 (i.e., on major surface 114)(not shown).

The physical thickness of the anti-reflective coating 120 may be in the range from about 0.1 μm to about 1 μm. In some instances, the physical thickness of the anti-reflective coating 120 may be in the range from about 0.01 μm to about 0.9 μm, from about 0.01 μm to about 0.8 μm, from about 0.01 μm to about 0.7 μm, from about 0.01 μm to about 0.6 μm, from about 0.01 μm to about 0.5 μm, from about 0.01 μm to about 0.4 μm, from about 0.01 μm to about 0.3 μm, from about 0.01 μm to about 0.2 μm, from about 0.01 μm to about 0.1 μm, from about 0.02 μm to about 1 μm, from about 0.03 μm to about 1 μm, from about 0.04 μm to about 1 μm, from about 0.05 μm to about 1 μm, from about 0.06 μm to about 1 μm, from about 0.07 μm to about 1 μm, from about 0.08 μm to about 1 μm, from about 0.09 μm to about 1 μm, from about 0.2 μm to about 1 μm, from about 0.3 μm to about 1 μm, from about 0.4 μm to about 1 μm, from about 0.5 μm to about 1 μm, from about 0.6 μm to about 1 μm, from about 0.7 μm to about 1 μm, from about 0.8 μm to about 1 μm, or from about 0.9 μm to about 1 μm, and all ranges and sub-ranges therebetween.

In one or more embodiments, the anti-reflective coating 120 may include a period 130 comprising two or more layers. In one or more embodiments, the two or more layers may be characterized as having different refractive indices from each another. In one embodiment, the period 130 includes a first low RI layer 130A and a second high RI layer 130B. The difference in the refractive index of the first low RI layer and the second high RI layer may be about 0.01 or greater, 0.05 or greater, 0.1 or greater or even 0.2 or greater.

As shown in FIG. 2, the anti-reflective coating 120 may include a plurality of periods (130). A single period includes include a first low RI layer 130A and a second high RI layer 130B, such that when a plurality of periods are provided, the first low RI layer 130A (designated for illustration as “L”) and the second high RI layer 130B (designated for illustration as “H”) alternate in the following sequence of layers: L/H/L/H or H/L/H/L, such that the first low RI layer and the second high RI layer appear to alternate along the physical thickness of the anti-reflective coating 120. In the example in FIG. 2, the anti-reflective coating 120 includes three periods. In some embodiments, the anti-reflective coating 120 may include up to 25 periods. For example, the anti-reflective coating 120 may include from about 2 to about 20 periods, from about 2 to about 15 periods, from about 2 to about 10 periods, from about 2 to about 12 periods, from about 3 to about 8 periods, from about 3 to about 6 periods.

In the embodiment shown in FIG. 2, the anti-reflective coating 120 may include an additional capping layer 131, which may include a lower refractive index material than the second high RI layer 130B.

In some embodiments, the period 130 may include one or more third layers 130C, as shown in FIG. 3. The third layer(s) 130C may have a low RI, a high RI or a medium RI. In some embodiments, the third layer(s) 130C may have the same RI as the first low RI layer 130A or the second high RI layer 130B. In other embodiments, the third layer(s) 130C may have a medium RI that is between the RI of the first low RI layer 130A and the RI of the second high RI layer 130B. Alternatively, the third layer(s) 130C may have a refractive index greater than the 2^(nd) high RI layer 130B. The third layer may be provided in the anti-reflective coating 120 in the following exemplary configurations: L_(third layer)/H/L/H/L; H_(third layer)/L/H/L/H; L/H/L/H/L_(third layer); H/L/H/L/H_(third layer); L_(third layer)/H/L/H/L/H_(third layer); H_(third layer)/L/H/L/H/L_(third layer); L_(third layer)/L/H/L/H; H_(third layer)/H/L/H/L; H/L/H/L/L_(third layer); L/H/L/H/H_(third layer); L_(third layer)/L/H/L/H/H_(third layer); H_(third layer)//H/L/H/L/L_(third layer); L/M_(third layer)/H/L/M/H; H/M/L/H/M/L; M/L/H/L/M; and other combinations. In these configurations, “L” without any subscript refers to the first low RI layer and “H” without any subscript refers to the second high RI layer. Reference to “L_(third sub-layer)” refers to a third layer having a low RI, “H_(third sub-layer)” refers to a third layer having a high RI and “M” refers to a third layer having a medium RI, all relative to the 1^(st) layer and the 2^(nd) layer.

As used herein, the terms “low RI”, “high RI” and “medium RI” refer to the relative values for the RI to another (e.g., low RI<medium RI<high RI). In one or more embodiments, the term “low RI” when used with the first low RI layer or with the third layer, includes a range from about 1.3 to about 1.7. In one or more embodiments, the term “high RI” when used with the second high RI layer or with the third layer, includes a range from about 1.6 to about 2.5. In some embodiments, the term “medium RI” when used with the third layer, includes a range from about 1.55 to about 1.8. In some instances, the ranges for low RI, high RI and medium RI may overlap; however, in most instances, the layers of the anti-reflective coating 120 have the general relationship regarding RI of: low RI<medium RI<high RI.

The third layer(s) 130C may be provided as a separate layer from a period 130 and may be disposed between the period or plurality of periods and an additional coating 140 instead of the capping 131 or in addition to the capping layer 131, as shown in FIG. 4. The third layer(s) may also be provided as a separate layer from a period 130 and may have disposed between the substrate 110 and the plurality of periods 130, as shown in FIG. 5.

Exemplary materials suitable for use in the anti-reflective coating 120 include: SiO₂, Al₂O₃, GeO₂, SiO, AlO_(x)N_(y), AlN, SiN_(x), SiO_(x)N_(y), Si_(u)Al_(v)O_(x)N_(y), Ta₂O₅, Nb₂O₅, TiO₂, ZrO₂, TiN, MgO, MgF₂, BaF₂, CaF₂, SnO₂, HfO₂, Y₂O₃, MoO₃, DyF₃, YbF₃, YF₃, CeF₃, polymers, fluoropolymers, plasma-polymerized polymers, siloxane polymers, silsesquioxanes, polyimides, fluorinated polyimides, polyetherimide, polyethersulfone, polyphenylsulfone, polycarbonate, polyethylene terephthalate, polyethylene naphthalate, acrylic polymers, urethane polymers, polymethylmethacrylate, other materials cited below as suitable for use in a scratch-resistant layer, and other materials known in the art. Some examples of suitable materials for use in the first low RI layer include SiO₂, Al₂O₃, GeO₂, SiO, AlO_(x)N_(y), SiO_(x)N_(y), Si_(u)Al_(v)O_(x)N_(y), MgO, MgAl₂O₄, MgF₂, BaF₂, CaF₂, DyF₃, YbF₃, YF₃, and CeF₃. The nitrogen content of the materials for use in the first low RI layer may be minimized (e.g., in materials such as Al₂O₃ and MgAl₂O₄). Some examples of suitable materials for use in the second high RI layer include Si_(u)Al_(v)O_(x)N_(y), Ta₂O₅, Nb₂O₅, AlN, Si₃N₄, AlO_(x)N_(y), SiO_(x)N_(y), HfO₂, TiO₂, ZrO₂, Y₂O₃, Al₂O₃, MoO₃ and diamond-like carbon. The oxygen content of the materials for the second high RI layer may be minimized, especially in SiNx or AlNx materials. The foregoing materials may be hydrogenated up to about 30% by weight. Where a material having a medium refractive index is desired, some embodiments may utilize AlN and/or SiO_(x)N_(y). The hardness of the second high RI layer may be characterized specifically. In some embodiments, the hardness, as measured by the Berkovitch Indenter Hardness Test may be about 8 GPa or greater, about 10 GPa or greater, about 12 GPa or greater, about 15 GPa or greater, about 18 GPa or greater, or about 20 GPa or greater. In some cases, the second high RI layer material may be deposited as a single layer (i.e. not as part of an anti-reflective coating), and this single layer may have a thickness between about 500 and 2000 nm for repeatable hardness determination.

In one or more embodiments at least one of the layer(s) of the anti-reflective coating 120 may include a specific optical thickness range. As used herein, the term “optical thickness” is determined by (n*d), where “n” refers to the RI of the sub-layer and “d” refers to the physical thickness of the layer. In one or more embodiments, at least one of the layers of the anti-reflective coating 120 may include an optical thickness in the range from about 2 nm to about 200 nm, from about 10 nm to about 100 nm, or from about 15 nm to about 100 nm. In some embodiments, all of the layers in the anti-reflective coating 120 may each have an optical thickness in the range from about 2 nm to about 200 nm, from about 10 nm to about 100 nm or from about 15 nm to about 100 nm. In some cases, at least one layer of the anti-reflective coating 120 has an optical thickness of about 50 nm or greater. In some cases, each of the first low RI layers have an optical thickness in the range from about 2 nm to about 200 nm, from about 10 nm to about 100 nm, or from about 15 nm to about 100 nm. In other cases, each of the second high RI layers have an optical thickness in the range from about 2 nm to about 200 nm, from about 10 nm to about 100 nm, or from about 15 nm to about 100 nm. In yet other cases, each of the third layers have an optical thickness in the range from about 2 nm to about 200 nm, from about 10 nm to about 100 nm, or from about 15 nm to about 100 nm.

In some embodiments, the thickness of one or more of the layers of the anti-reflective coating 120 may be minimized. In one or more embodiments, the thickness of the thickness of the high RI layer(s) and/or the medium RI layer(s) are minimized such that they are less than about 500 nm. In one or more embodiments, the combined thickness of the high RI layer(s), the medium RI (layers) and/or the combination of the high RI and medium RI layers is less than about 500 nm.

In one or more embodiments, the anti-reflective coating 120 has a physical thickness of about 800 nm or less. The anti-reflective coating 120 may have a physical thickness in the range from about 10 nm to about 800 nm, from about 50 nm to about 800 nm, from about 100 nm to about 800 nm, from about 150 nm to about 800 nm, from about 200 nm to about 800 nm, from about 10 nm to about 750 nm, from about 10 nm to about 700 nm, from about 10 nm to about 650 nm, from about 10 nm to about 600 nm, from about 10 nm to about 550 nm, from about 10 nm to about 500 nm, from about 10 nm to about 450 nm, from about 10 nm to about 400 nm, from about 10 nm to about 350 nm, from about 10 nm to about 300 nm, from about 50 to about 300, and all ranges and sub-ranges therebetween.

In one or more embodiments, the combined physical thickness of the second high RI layer(s) may be characterized. For example, in some embodiments, the combined thickness of the second high RI layer(s) may be about 100 nm or greater, about 150 nm or greater, about 200 nm or greater, about 500 nm or greater. The combined thickness is the calculated combination of the thicknesses of the individual high RI layer(s) in the anti-reflective coating 120, even when there are intervening low RI layer(s) or other layer(s). In some embodiments, the combined physical thickness of the second high RI layer(s), which may also comprise a high-hardness material (e.g., a nitride or an oxynitride), may be greater than 30% of the total physical thickness of the anti-reflective coating. For example, the combined physical thickness of the second high RI layer(s) may be about 40% or greater, about 50% or greater, about 60% or greater, about 70% or greater, about 75% or greater, or even about 80% or greater, of the total physical thickness of the anti-reflective coating.

In some embodiments, greater proportions of hard and high-index material within the anti-reflective coating can also simultaneously be made to also exhibit low reflectance, low color, and high abrasion resistance as further described elsewhere herein.

In some embodiments, the anti-reflective coating 120 exhibits an average light reflectance of about 2% or less, 1.5% or less, 0.75% or less, 0.5% or less, 0.25% or less, 0.1% or less, or even 0.05% or less over the optical wavelength regime, when measured at the anti-reflective surface 122 (e.g., when removing the reflections from an uncoated back surface (e.g., 114 in FIG. 1) of the article, such as through using index-matching oils on the back surface coupled to an absorber, or other known methods). In some instances, the anti-reflective coating 120 may exhibit such average light reflectance over other wavelength ranges such as from about 450 nm to about 650 nm, from about 420 nm to about 680 nm, from about 420 nm to about 700 nm, from about 420 nm to about 740 nm, from about 420 nm to about 850 nm, or from about 420 nm to about 950 nm. In some embodiments, the anti-reflective surface 122 exhibits an average light transmission of about 90% or greater, 92% or greater, 94% or greater, 96% or greater, or 98% or greater, over the optical wavelength regime. Unless otherwise specified, the average reflectance or transmittance is measured at an incident illumination angle of 0 degrees (however, such measurements may be provided at incident illumination angles of 45 degrees or 60 degrees).

The article 100 may include one or more additional coatings 140 disposed on the anti-reflective coating, as shown in FIG. 6. In one or more embodiments, the additional coating may include an easy-to-clean coating. An example of a suitable an easy-to-clean coating is described in U.S. patent application Ser. No. 13/690,904, entitled “PROCESS FOR MAKING OF GLASS ARTICLES WITH OPTICAL AND EASY-TO-CLEAN COATINGS,” filed on Nov. 30, 2012, which is incorporated herein in its entirety by reference. The easy-to-clean coating may have a thickness in the range from about 5 nm to about 50 nm and may include known materials such as fluorinated silanes. In some embodiments, the easy-to-clean coating may have a thickness in the range from about 1 nm to about 40 nm, from about 1 nm to about 30 nm, from about 1 nm to about 25 nm, from about 1 nm to about 20 nm, from about 1 nm to about 15 nm, from about 1 nm to about 10 nm, from about 5 nm to about 50 nm, from about 10 nm to about 50 nm, from about 15 nm to about 50 nm, from about 7 nm to about 20 nm, from about 7 nm to about 15 nm, from about 7 nm to about 12 nm or from about 7 nm to about 10 nm, and all ranges and sub-ranges therebetween.

The additional coating 140 may include a scratch resistant coating. A scratch resistant coating may also be included in one of the layers of the anti-reflective coating 120. Exemplary materials used in the scratch resistant coating may include an inorganic carbide, nitride, oxide, diamond-like material, or combination of these. Examples of suitable materials for the scratch resistant coating include metal oxides, metal nitrides, metal oxynitride, metal carbides, metal oxycarbides, and/or combinations thereof combination thereof. Exemplary metals include B, Al, Si, Ti, V, Cr, Y, Zr, Nb, Mo, Sn, Hf, Ta and W. Specific examples of materials that may be utilized in the scratch resistant coating may include Al₂O₃, AlN, AlO_(x)N_(y), Si₃N₄, SiO_(x)N_(y), Si_(u)Al_(v)O_(x)N_(y), diamond, diamond-like carbon, Si_(x)C_(y), Si_(x)O_(y)C_(z), ZrO₂, TiO_(x)N_(y) and combinations thereof.

In some embodiments, the additional coating 140 includes a combination of easy-to-clean material and scratch resistant material. In one example, the combination includes an easy-to-clean material and diamond-like carbon. Such additional coatings 140 may have a thickness in the range from about 5 nm to about 20 nm. The constituents of the additional coating 140 may be provided in separate layers. For example, the diamond-like carbon may be disposed as a first layer and the easy-to clean can be disposed as a second layer on the first layer of diamond-like carbon. The thicknesses of the first layer and the second layer may be in the ranges provided above for the additional coating. For example, the first layer of diamond-like carbon may have a thickness of about 1 nm to about 20 nm or from about 4 nm to about 15 nm (or more specifically about 10 nm) and the second layer of easy-to-clean may have a thickness of about 1 nm to about 10 nm (or more specifically about 6 nm). The diamond-like coating may include tetrahedral amorphous carbon (Ta—C), Ta—C:H, and/or a-C—H.

A second aspect of this disclosure pertains to a method for forming the articles described herein. In one embodiment, the method includes providing a substrate having a major surface in a coating chamber, forming a vacuum in the coating chamber, forming a durable anti-reflective coating having a thickness of about 1 μm or less on the major surface, optionally forming an additional coating comprising at least one of an easy-to-clean coating and a scratch resistant coating, on the anti-reflective coating, and removing the substrate from the coating chamber. In one or more embodiments, the anti-reflective coating and the additional coating are formed in either the same coating chamber or without breaking vacuum in separate coating chambers.

In one or more embodiments, the method may include loading the substrate on carriers which are then used to move the substrate in and out of different coating chambers, under load lock conditions so that a vacuum is preserved as the substrate is moved.

The anti-reflective coating 120 and/or the additional coating 140 may be formed using various deposition methods such as vacuum deposition techniques, for example, chemical vapor deposition (e.g., plasma enhanced chemical vapor deposition (PECVD), low-pressure chemical vapor deposition, atmospheric pressure chemical vapor deposition, and plasma-enhanced atmospheric pressure chemical vapor deposition), physical vapor deposition (e.g., reactive or nonreactive sputtering or laser ablation), thermal or e-beam evaporation and/or atomic layer deposition. Liquid-based methods may also be used such as spraying or slot coating. Where vacuum deposition is utilized, inline processes may be used to form the anti-reflective coating 120 and/or the additional coating 140 in one deposition run. In some instances, the vacuum deposition can be made by a linear PECVD source.

In some embodiments, the method may include controlling the thickness of the anti-reflective coating 120 and/or the additional coating 140 so that it does not vary by more than about 4% along at least about 80% of the area of the anti-reflective surface 122 or from the target thickness for each layer at any point along the substrate area. In some embodiments, the thickness of the anti-reflective layer coating 120 and/or the additional coating 140 so that it does not vary by more than about 4% along at least about 95% of the area of the anti-reflective surface 122.

EXAMPLES

Various embodiments will be further clarified by the following examples. In the Examples, it should be noted that AlO_(x)N_(y) and SiuAlvOxNy were found to be substantially interchangeable as the high-index material in the modeled examples, with only minor process adjustments necessary to re-create the targeted refractive index dispersion values and layer thickness designs provided, which are apparent to one of ordinary skill in the art.

Example 1

Example 1 was formed by providing a glass substrate having a nominal composition of 69 mol % SiO₂, 10 mol % Al₂O₃, 15 mol % Na₂O, and 5 mol % MgO and disposing an anti-reflective coating having five layers on the glass substrate, as shown in Table land in FIG. 7 using a plasma-enhanced chemical vapor deposition (PECVD) process.

TABLE 1 Anti-reflective coating attributes for Example 1. Layer Reference No. Material Thickness Ambient medium — Air — Third layer 131 SiN_(x)  9.55 nm l^(st) Period 1^(st) low RI layer 130B SiO₂ 64.34 nm 2^(nd) high RI layer 130A SiN_(x) 51.20 nm 2^(nd) Period 1^(st) low RI layer 130B SiO₂ 28.89 nm 2^(nd) high RI layer 130A SiN_(x) 24.10 nm Substrate 110 Glass

The refractive index of the second high RI layers was in the range from about 1.6 to about 2.1 depending on the amount of nitrogen present in those layers. The resulting article was transparent and exhibited abrasion resistance after 2000 cycles of linear abrasion test.

FIG. 8 shows the reflectance spectrum for Example 1 over the optical wavelength regime. Example 1 exhibited a reflectance of less than about 0.5% along a portion of the optical wavelength regime and a reflectance of about 2% or less over the entire optical wavelength regime.

Modeled Example 2

Modeled Example 2 was prepared using the same glass substrate as used in Example 1, as shown in Table 2.

TABLE 2 Anti-reflective coating and easy-to-clean coating attributes for Modeled Example 2. Refractive Layer Material Thickness Index Ambient medium Air 1 Additional coating easy-to- 10 nm 1.407 clean 1^(st) Period 1^(st) low RI layer SiO₂ 84 nm 1.463 2^(nd) high RI layer SiN_(x) 52 nm 2.113 2^(nd) Period 1^(st) low RI layer SiO₂ 15 nm 1.463 2^(nd) high RI layer SiN_(x) 47 nm 2.113 3^(rd) Period 1^(st) low RI layer SiO₂ 41 nm 1.463 2^(nd) high RI layer SiN_(x) 13 nm 2.113 Substrate Glass 1.523

The reflectance of Modeled Example 2 was simulated as shown in FIG. 9 (the thicknesses shown are not exact and intended to be illustrative). As shown in FIG. 9, the reflectance of Modeled Example 2 was less than about 0.5% over the wavelength ranges from about 420 nm to about 620 nm and was less than 1% over the entire optical wavelength regime.

It should be noted that Modeled Example 2 may be modified to include thicker or thinner additional coatings of easy-to-clean (e.g., from about 7 nm to about 15 nm), having a refractive index in the range from about 1.2 to about 1.5, depending on the materials selected and the formation process utilized.

Modeled Example 3

Modeled Example 3 was prepared using the same glass substrate as used in Example 1 and included an anti-reflective coating, a DLC coating having a thickness of 6 nm or 10 nm disposed on the anti-reflective coating, and an easy-to-clean coating on the DLC coating as shown in Table 3.

TABLE 3 Anti-reflective coating, easy-to-clean coating and DLC coating attributes for Modeled Example 3. Refractive Layer Material Thickness Index Ambient medium Air 1 Additional coating Easy-to- 1.407 clean Additional coating DLC 6 nm or 10 nm 2.137 1^(st) Period l^(st) low RI layer SiO₂ 1.463 2^(nd) high RI layer TiO₂ 2.457 2^(nd) Period 1^(st) low RI layer SiO₂ 1.463 2^(nd) high RI layer TiO₂ 2.457 3^(rd) Period 1^(st) low RI layer SiO₂ 1.463 2^(nd) high RI layer TiO₂ 2.457 Substrate Glass 1.523

The reflectance of Modeled Example 3 was simulated for the different DLC coating thicknesses, and is shown together in FIG. 10. As shown in FIG. 10, the reflectance of Modeled Example 3 for both DLC coating thicknesses were both less than about 1% over the optical wavelength regime. In the embodiment where the DLC coating was about 6 nm, the reflectance was even lower (i.e., less than about 0.5%) over the entire optical wavelength regime. For clarity, the reflectance spectrum for Modeled Example 3 with the DLC coating having a thickness of 6 nm is shown in FIG. 11.

Modeled Examples 4-8

Examples 4-8 used modeling to understand the reflectance spectra of articles that included embodiments of a durable anti-reflective coating, as described herein. In Modeled Examples 4-8, Si_(u)Al_(v)O_(x)N_(y) and SiO₂ layers, and a strengthened aluminosilicate glass substrate having a nominal composition of about 58 mol % SiO₂, 17 mol % Al₂O₃, 17 mol % Na₂O, 3 mol % MgO, 0.1 mol % SnO, and 6.5 mol % P₂O₅ were used.

To determine the refractive index dispersion curves for the coating materials, layers of each coating material were formed onto silicon wafers by DC, RF or RF superimposed DC reactive sputtering from a silicon, aluminum, silicon and aluminum combined or co-sputtered, or magnesium fluoride target (respectively) at a temperature of about 50° C. using ion assist. The wafer was heated to 200° C. during deposition of some layers and targets having a 3 inch diameter were used. Reactive gases used included nitrogen, fluorine and oxygen; argon was used as the inert gas. The RF power was supplied to the silicon target at 13.56 Mhz and DC power was supplied to the Si target, Al target and other targets.

The refractive indices (as a function of wavelength) of each of the formed layers and the glass substrate were measured using spectroscopic ellipsometry. The refractive indices thus measured were then used to calculate reflectance spectra for Modeled Examples 4-8. The modeled examples use a single refractive index value in their descriptive tables for convenience, which corresponds to a point selected from the dispersion curves at about 550 nm wavelength.

Example 4 included a 6-layer anti-reflective coating, including layers 210, 220, 230, 240, 250 and 260 sequentially disposed on top of one another, disposed on a strengthened aluminosilicate glass substrate 200 as shown in FIG. 12 (the thicknesses shown are not exact and intended to be illustrative) and in Table 7.

TABLE 7 Attributes for Modeled Example 4. Peri- Refractive Modeled Physical Layer ods Material Index Thickness Ambient — Air 1 medium Anti- 1 SiO₂-a (260) 1.4826 90 nm reflective Si_(u)Al_(v)O_(x)N_(y) (250) 2.015 80 nm Coating 2 SiO₂-a (240) 1.4826 12 nm Si_(u)Al_(v)O_(x)N_(y) (230) 2.015 40 nm 3 SiO₂-a (220) 1.4826 46 nm Si_(u)Al_(v)O_(x)N_(y) (210) 2.015 10 nm Substrate — AS Glass 1.51005 — Total Coating 278 nm Thickness

The total thickness of the Si_(u)Al_(v)O_(x)N_(y) layers, which have a higher hardness as measured by the Berkovitch Indenter Hardness Test, as compared to the SiO₂ layers, is 130 nm, which comprises about 47% of the entire thickness of the coating. Anti-reflective coatings having a structure similar to the anti-reflective coating of Modeled Example 4 were fabricated by DC/RF sputtering. These coatings were found to exhibit an abrasion resistance similar to or better than the bare glass substrate and substantially improved abrasion resistance over convention, oxide-only anti-reflective coatings, as illustrated by Example 15. The article according to Example 4 exhibited an abrasion similar to the abrasion of the bare glass substrate (without an anti-reflective coating disposed thereon).

The reflectance of a single side of the article of Example 4 was calculated at different viewing incident illumination angles or angle of illumination (“AOI”) and the resulting reflectance spectra is shown in FIG. 13. The reflected color, based on a 10° observer under a D65 illuminant and a F2 illuminant was also measured and the a* and b* values are plotted as the incident illumination angle or AOI changed from 0 degrees to about 60 degrees from normal incidence at regular increments. The plot showing the reflected color is shown in FIG. 14.

Example 5 included a 9-layer anti-reflective coating, including layers 310 (third layer), 320, 330, 340, 350, 360, 370, 380, and 390 sequentially disposed on top of one another, disposed on a strengthened aluminosilicate glass substrate 200, as shown in FIG. 15 (the thicknesses shown in FIG. 15 are not exact and intended to be illustrative) and the relative thicknesses of the layers are shown in Table 8.

TABLE 8 Attributes for Modeled Example 5. Peri- Refractive Modeled Physical Layer ods Material Index Thickness Ambient — Air 1 medium Anti- 1 SiO₂-a (390) 1.4826 88 nm reflective Si_(u)Al_(v)O_(x)N_(y) (380) 2.015 81 nm coating 2 SiO₂-a (370) 1.4826 29 nm Si_(u)Al_(v)O_(x)N_(y) (360) 2.015 22 nm 3 SiO₂-a (350) 1.4826 120 nm Si_(u)Al_(v)O_(x)N_(y) (340) 2.015 14 nm 4 SiO₂-a (330) 1.4826 68 nm Si_(u)Al_(v)O_(x)N_(y) (320) 2.015 16 nm — SiO₂-a (310) 1.4826 26 nm Substrate — AS Glass 1.51005 — Total Coating 464 nm Thickness

In Modeled Example 5, the total thickness of the Si_(u)Al_(v)O_(x)N_(y) layers, which have a higher hardness as measured by the Berkovitch Indenter Hardness Test as compared to the SiO₂ layers, is 133 nm, which comprises about 29% of the entire thickness of the coating. The article according to Example 5 is believed to exhibit an abrasion similar to the abrasion of the bare glass substrate (without an anti-reflective coating disposed thereon).

The reflectance of a single side of the article of Example 5 was calculated at different viewing incident illumination angles or angle of illumination (“AOI”) and the resulting reflectance spectra is shown in FIG. 16. The reflected color, based on a 10° observer under a D65 illuminant was also measured and the a* and b* values are plotted as the incident illumination angle or AOI changed from 0 degrees to about 60 degrees from normal incidence at regular increments. The plot showing the reflected color is shown in FIG. 17.

Example 6 included a 10-layer anti-reflective coating, including layers 400, 410, 420, 430, 440, 450, 460, 470, 480, and 490 sequentially disposed on top of one another, disposed on a strengthened aluminosilicate glass substrate 200, as shown in FIG. 18 (the thicknesses shown in FIG. 18 are not exact and intended to be illustrative) and Table 9.

TABLE 9 Attributes for Modeled Example 16. Peri- Refractive Modeled Physical Layer ods Material Index Thickness Ambient — Air 1 medium Anti- 1 SiO₂-a (490) 1.4826 86 nm reflective Si_(u)Al_(v)O_(x)N_(y) (480) 2.015 152 nm coating 2 SiO₂-a (470) 1.4826 7 nm Si_(u)Al_(v)O_(x)N_(y) (460) 2.015 350 nm (but variable in the range from about 100 nm to about 2000 nm) 3 SiO₂-a (450) 1.4826 9 nm Si_(u)Al_(v)O_(x)N_(y) (440) 2.015 43 nm 4 SiO₂-a (430) 1.4826 31 nm Si_(u)Al_(v)O_(x)N_(y) (420) 2.015 25 nm 5 SiO₂-a (410) 1.4826 53 nm Si_(u)Al_(v)O_(x)N_(y) (400) 2.015 8 nm Substrate — AS Glass 1.51005 — Total Coating 764 nm Thickness

Layers 470, 480 and 490 are impedance matched to air and layers 400, 410, 420, 430, 440 and 450 are impedance matched to the glass substrate. Accordingly, layer 460 may be modified to have a thickness in the range from about 0 mm to about 500 nm or from about 100 nm to about 2000 nm, without influencing the optical properties of the anti-reflective coating or the article.

In Modeled Example 6, the total thickness of the Si_(u)Al_(v)O_(x)N_(y) layers, which have a higher hardness as measured by the Berkovitch Indenter Hardness Test as compared to the SiO₂ layers, is 578 nm, which comprises about 76% of the entire thickness of the coating. Anti-reflective coatings having a structure very similar to Modeled Example 6 were fabricated by DC/RF sputtering, and exhibited an abrasion resistance substantially better than the bare glass substrate, and substantially better abrasion resistance than conventional oxide-only anti-reflective coatings.

The reflectance of a single side of the article of Example 6 was calculated at different viewing incident illumination angles or angle of illumination (“AOI”) and the resulting reflectance spectra is shown in FIG. 19. The reflected color, based on a 10° observer under a D65 illuminant and a F2 illuminant was also measured and the a* and b* values are plotted as the incident illumination angle or AOI changed from 0 degrees to about 60 degrees from normal incidence at regular increments. The plot showing the reflected color is shown in FIG. 20.

Modeled Example 7 included a 12-layer anti-reflective coating, including layers 500, 505, 510, 515, 520, 530, 540, 550, 560, 570, 580, and 590 sequentially disposed on top of one another, disposed on a strengthened aluminosilicate glass substrate 200, as shown in FIG. 21 (the thicknesses shown in FIG. 21 are not exact and intended to be illustrative) and in Table 10.

TABLE 10 Attributes for Modeled Example 7. Peri- Refractive Modeled Physical Layer ods Material Index Thickness Ambient — Air 1 medium Anti- 1 SiO₂-a (590) 1.4826 87 nm reflective Si_(u)Al_(v)O_(x)N_(y) (580) 2.015 148 nm coating 2 SiO₂-a (570) 1.4826 19 nm Si_(u)Al_(v)O_(x)N_(y) (560) 2.015 49 nm 3 SiO₂-a (550) 1.4826 11 nm Si_(u)Al_(v)O_(x)N_(y) (540) 2.015 500 nm (but variable in the range from about 100 nm to about 5000 nm) 4 SiO₂-a (530) 1.4826 10 nm Si_(u)Al_(v)O_(x)N_(y) (520) 2.015 44 nm 5 SiO₂-a (515) 1.4826 32 nm Si_(u)Al_(v)O_(x)N_(y) (510) 2.015 25 nm 6 SiO₂-a (505) 1.4826 56 nm Si_(u)Al_(v)O_(x)N_(y) (500) 2.015 8 nm Substrate — AS Glass 1.51005 — Total Coating 989 nm Thickness

Layers 550, 560, 570, 580, and 590 are impedance matched to air and layers and 500, 505, 510, 515, 520 and 530 are impedance matched to the glass substrate. Accordingly, layer 540 may be modified to have a thickness in the range from about 0 mm to about 5000 nm or from about 100 nm to about 2500 nm, without influencing the optical properties of the anti-reflective coating or the article.

In Modeled Example 7, the total thickness of the Si_(u)Al_(v)O_(x)N_(y) layers, which have a higher hardness as measured by the Berkovitch Indenter Hardness Test as compared to the SiO₂ layers, is 774 nm, which comprises about 78% of the entire thickness of the coating. Anti-reflective coatings having a structure very similar to Modeled Example 7 were fabricated by DC/RF sputtering, and exhibited an abrasion resistance substantially better than the bare glass substrate, and substantially better abrasion resistance than conventional oxide-only anti-reflective coatings, as illustrated by Example 16 below.

The reflectance of a single side of the article of Example 7 was calculated at different viewing incident illumination angles or angle of illumination (“AOI”) and the resulting reflectance spectra is shown in FIG. 22. The reflected color, based on a 10° observer under a D65 illuminant and a F2 illuminant was also measured and the a* and b* values are plotted as the incident illumination angle or AOI changed from 0 degrees to about 60 degrees from normal incidence at regular increments. The plot showing the reflected color is shown in FIG. 23.

Example 8 included a 14-layer anti-reflective coating, including layers 600, 605, 610, 615, 620, 625, 630, 635, 640, 650, 660, 670, 680, and 690 sequentially disposed on top of one another, disposed on a strengthened aluminosilicate glass substrate 200, as shown in FIG. 24 (the thicknesses shown in FIG. 24 are not exact and intended to be illustrative) and the relative thicknesses of the layers are shown in Table 11.

TABLE 11 Attributes for Modeled Example 8. Peri- Refractive Modeled Physical Layer ods Material Index Thickness Ambient — Air 1 medium Anti- 1 SiO₂-a (690) 1.4826 87 nm reflective Si_(u)Al_(v)O_(x)N_(y) (680) 2.015 251 nm coating 2 SiO₂-a (670) 1.4826 27 nm Si_(u)Al_(v)O_(x)N_(y) (660) 2.015 11 nm 3 SiO₂-a (650) 1.4826 149 nm Si_(u)Al_(v)O_(x)N_(y) (640) 2.015 28 nm 4 SiO₂-a (635) 1.4826 17 nm Si_(u)Al_(v)O_(x)N_(y) (630) 2.015 217 nm 5 SiO₂-a (625) 1.4826 22 nm Si_(u)Al_(v)O_(x)N_(y) (620) 2.015 42 nm 6 SiO₂-a (615) 1.4826 31 nm SiuAlvOxNy 2.015 156 nm (610) 7 SiO₂-a (605) 1.4826 38 nm Si_(u)Al_(v)O_(x)N_(y) (600) 2.015 17 nm Substrate — AS Glass 1.51005 — Total Coating 1093 nm Thickness

The total thickness of the Si_(u)Al_(v)O_(x)N_(y) layers, which have a higher hardness as measured by the Berkovitch Indenter Hardness Test as compared to the SiO₂ layers, is 722 nm, which comprises about 66% of the entire thickness of the coating

The reflectance of a single side of the article of Example 8 was calculated at different viewing incident illumination angles or angle of illumination (“AOI”) and the resulting reflectance spectra is shown in FIG. 25. The reflected color, based on a 10° observer under a D65 illuminant and a F2 illuminant was also measured and the a* and b* values are plotted as the incident illumination angle or AOI changed from 0 degrees to about 60 degrees from normal incidence at regular increments. The plot showing the reflected color is shown in FIG. 26.

Modeled Examples 9, 10A & 10B

Modeled Examples 9, 10A and 10B used the refractive indices and dispersion curves used for Modeled Examples 4-8, and shown above in Tables 4-5 to calculate reflectance spectra of various anti-reflective coating 120 designs.

Modeled Example 9 included a 6-layer anti-reflective coating sequentially disposed on top of one another, disposed on a strengthened aluminosilicate glass substrate 200. The relative thicknesses of the layers are shown in Table 12.

TABLE 12 Attributes for Modeled Example 9. Peri- Refractive Modeled Physical Layer ods Material Index Thickness Ambient — Air 1 medium Anti- 1 SiO₂-a 1.4826 95 nm reflective Si_(u)Al_(v)O_(x)N_(y) 2.015 167 nm coating 2 SiO₂-a 1.4826 31 nm Si_(u)Al_(v)O_(x)N_(y) 2.015 37 nm 3 SiO₂-a 1.4826 57 nm Si_(u)Al_(v)O_(x)N_(y) 2.015 14 nm Substrate — AS Glass 1.51005

The reflectance of a single side of the article of Modeled Example 9 was calculated at different viewing incident illumination angles or angle of illumination (“AOI”) and the resulting reflectance spectra is shown in FIG. 27. The reflected color, based on a 10° observer under a D65 illuminant and a F2 illuminant was also measured and the a* and b* values are plotted as the incident illumination angle or AOI changed from 0 degrees to about 60 degrees from normal incidence at regular increments. The plot showing the reflected color is shown in FIG. 28.

Modeled Examples 10A and 10B each included an 8-layer anti-reflective coating. Each layer of the coating was sequentially disposed on top of one another, and disposed on a strengthened aluminosilicate glass substrate 200. The relative thicknesses of the layers are shown in Table 13.

TABLE 13 Attributes for Modeled Examples 10A and 10B. Peri- Refractive Modeled Physical Layer ods Material Index Thicknesses Ambient — Air 1 10A 10B medium Anti- 1 SiO₂-a 1.4826 107 nm 106 nm reflective Si_(u)Al_(v)O_(x)N_(y) 2.015 44 nm 42 nm coating 2 SiO₂-a 1.4826 10 nm 12 nm Si_(u)Al_(v)O_(x)N_(y) 2.015 86 nm 84 nm 3 SiO₂-a 1.4826 26 nm 27 nm Si_(u)Al_(v)O_(x)N_(y) 2.015 27 nm 26 nm 4 SiO₂-a 1.4826 47 nm 48 nm Si_(u)Al_(v)O_(x)N_(y) 2.015 9 nm 7 nm Substrate — AS Glass 1.51005

The reflectance values of a single side of the article of Example 10A and Example 10B were calculated at different viewing incident illumination angles or angle of illumination (“AOI”) and the resulting reflectance spectra is shown in FIGS. 29 and 30, respectively. The reflected color, based on a 10° observer under a D65 illuminant and a F2 illuminant was also measured and the a* and b* values are plotted as the incident illumination angle or AOI changed from 0 degrees to about 60 degrees from normal incidence at regular increments. The plots showing the reflected color for Examples 10A and 10B is shown in FIGS. 31-32, respectively.

The optical performance of Modeled Examples 4, 7, 9, 10A and 10B was compared to Modeled Comparative Example 11, which included a 6-layer anti-reflective coating of alternating Nb₂O₅ and SiO₂ layers and a hydrophobic coating disposed on the anti-reflective coating. To generate Modeled Comparative Example 11, ion-assisted e-beam deposition was used to deposit a single layer of Nb₂O₅ onto a silicon wafer and a single layer of SiO₂ onto a silicon wafer. The refractive indices as a function of wavelength for these layers were measured using spectroscopic ellipsometry. The measured refractive indices were then used in Modeled Comparative Example 11. The optical performance evaluated includes average reflectance over the wavelength range from about 450 nm to about 650 nm and color shift (with reference to a* and b* coordinates (−1, −1), using the equation √((a*_(example)−(−1))²+(b*_(example)−(−1))²)) when viewed at an incident illumination angles in the range from about 0 degrees to about 60 degrees from normal incidence under F02 and D65 illuminants. Table 14 shows the average reflectance and the greatest color shift of Modeled Examples 4, 7, 9, 10A and 10B and Modeled Comparative Example 11.

TABLE 14 Average Reflectance and Color Shift for Modeled Examples 4, 7, 9, 10A and 10B and Modeled Comparative Example 11. Avg. Reflec- Color Shift Refer- tance 450-650 enced to (a*, b*) = Ex. nm (%) (−1, −1) Modeled Example 4, 6-layer 0.5 4.0 Si_(u)Al_(v)O_(x)N_(y) or AlO_(x)N_(y)/SiO₂ Modeled Example 7, 12-layer 1.0 2.5 Si_(u)Al_(v)O_(x)N_(y) or AlO_(x)N_(y)/SiO₂ Modeled Example 9, 6-layer 0.8 3.6 Si_(u)Al_(v)O_(x)N_(y) or AlO_(x)N_(y)/SiO₂ Modeled Example 10A, 8-layer 1.5 1.2 Si_(u)Al_(v)O_(x)N_(y) or AlO_(x)N_(y)/SiO₂ Modeled Example 10B, 8-layer 2.0 0.6 Si_(u)Al_(v)O_(x)N_(y) or AlO_(x)N_(y)/SiO₂ Modeled Comp. Ex. 11, 6-layer 0.3 7.9 Nb2O5/SiO2/hydrophobic coating

As shown in Table 14, while Modeled Comparative 11 exhibited the lowest average reflectance, it also exhibited the greatest color shift. Modeled Example 4 exhibited comparable reflectance and a significantly reduced color shift. Modeled Examples 7, 9, 10A and 10B had even less color shift though, reflectance was increased slightly.

Examples 12-18

Examples 12-18 included either bare aluminosilicate glass substrates (with no coatings) or aluminosilicate glass substrates with various anti-reflective or hard coatings as shown in Table 15. The aluminosilicate glass substrates were chemically strengthened and exhibited a compressive stress in the range from about 700 MPa to about 900 MPa and depths of compressive stress layer values in the range from about 40 μm to about 50 μm. The anti-reflective coatings were deposited using reactive DC sputtering, e-beam evaporation, and reactive DC and RF sputtering. The anti-reflective coatings included layers of SiO₂, Si_(u)Al_(v)O_(x)N_(y), AlO_(x)N_(y), and Nb₂O₅. SiO₂ layers were formed by either DC reactive sputtering from a Si target at about 200° C. with ion assist or by ion-assisted e-beam deposition, as indicated in Table 15. Nb₂O₅ layers were deposited by ion-assisted e-beam deposition. Layers of Si_(u)Al_(v)O_(x)N_(y) were deposited by DC reactive sputtering combined with RF superimposed DC sputtering using a substrate heated to 200° C. substrate heating with ion assist. Si_(u)Al_(v)O_(x)N_(y) layers were made by reactive sputtering in an AJA-Industries Sputter Deposition Tool. The targets used to form the Si_(u)Al_(v)O_(x)N_(y) layers were 3″ diameter Si and 3″ diameter Al. The reactive gasses were nitrogen and oxygen, and the “working” (or inert) gas was Argon. The power supplied to the Si target was radio frequency (RF) at 13.56 Mhz. The power supplied to the Al target was DC. It should be noted that layers of AlO_(x)N_(y) could be substituted for the layers of Si_(u)Al_(v)O_(x)N_(y) layers and can be formed using the same or similar process used to form such layers. Both Si_(u)Al_(v)O_(x)N_(y), and AlO_(x)N_(y) layers can be made to exhibit a refractive index at 550 nm of about 1.95 and a measured hardness greater than 15 GPa measured using the Berkovitch Indenter Hardness Test.

TABLE 15 Anti-reflective coating structures for Examples 12-18. Example Coating Structure Ex. 12 6-layers, having the same structure and materials as modeled Ex. 4 Ex. 13 12-layers, having the same structure and materials as modeled Example 7 Comparative 6L having the same structure and materials as Modeled Ex. 14 Comparative Example 11 Comparative chemically strengthened glass with hydrophobic Ex. 15 coating only Comprative single layer of Si_(u)Al_(v)O_(x)N_(y) having a thickness of 186 nm Ex. 16 Comparative single layer of Si_(u)Al_(v)O_(x)N_(y) having a thickness of 478 nm Ex. 17 Comparative chemically strengthened glass with no coatings (bare) Ex. 18

Table 16 shows the abrasion resistance of Examples 12-13 and Comparative Examples 14-18, as measured in terms of measured scattered light intensity (CCBTDF, 1/steradian) and transmission haze (with 8 mm aperture) after subjecting the samples to the Taber Test. The average reflectance was measured at the anti-reflective surface without abrasion (single surface measurement, subtracting out 4% reflectance from the opposite, uncoated surface).

TABLE 16 Average Reflectance (without abrasion) and abrasion resistance, as measured by scattered light intensity and transmission haze (after being subjected to the Taber Test) for Examples 12-13 and Comparative Examples 14-18. Range of Avg. Trans- Reflec mission tance- Scattered light intensity - Haze (Non- Avg. +/− Std. Dev. With abraded) (CCBTDF, 1/steradian) 7 mm 450-650 Example At 20 degrees At 40 degrees aperture nm (%) Ex. 12 0.012 +/− 0.004 0.004 +/− 0.002 0.1-0.2 0.7 Ex. 13 0.008 +/− 0.006 0.002 +/− 0.001 0   0.7 Comparative 0.13 +/− 0.04 0.09 +/− 0.03 1.3-2.8 0.5 Ex. 14 Comparative 0.022 +/− 0.015 0.008 +/− 0.004 0.25-0.35 4.0 Ex. 15 Comparative 0.03 +/− 0.01 0.008 +/− 0.006 0.8 8.4 Ex. 16 Comparative 0.018 +/− 0.001 0.008 +/− 0.002 0.3 6.0 Ex. 17 Comparative 0.021 +/− 0.004 0.007 +/− 0.003 0.1-0.4 4.0 Ex. 18 Comparative 0.002 +/− 0.001  0.001 +/− 0.0004   0-0.2 4.0 Ex. 18 (Without Abrading)

As shown in Table 16, Examples 12 and 13 approached the scattered light intensity of the Comparative Ex. 18 without abrading (or without being subjected to the Taber Test) at 40 degrees, indicating superior abrasion resistance. Examples 12 and 13 also exhibited the least scattered light intensity at 20 degrees, of all the samples after being subjected to the Taber Test. The transmission haze of both Examples 12 and 13 was substantially the same as the transmission haze for Comparative Ex. 18 without abrading. The average reflectance of Examples 12 and 13 was significantly improved over Comparative Example 18, with only Comparative Example 14 exhibiting less average reflectance.

FIG. 33 is a graph shows the scattered light intensity (CCBTDF, 1/steradian) measurements of Table 16, along polar angles orthogonal to abrasion direction for Examples 12-13 and Comparative Examples 15-17, with and without being subjected to the Taber Test. Lower scattering intensity values indicate less severe abrasion and thus greater abrasion resistance (and lower abrasion visibility in human inspection trials).

The abrasion resistance of Examples 12-13 and Comparative Examples 14, 17-18 was evaluated by AFM roughness, after being subjected to the Taber Test. Table 17 shows AFM roughness statistics (average and std. dev.) reported for 5 scans of an 80×80 micron area within the abraded region. As shown in Table 17, Examples 12 and 13 exhibited very low roughness, as compared to Comparative Ex. 14 and 18. Comparative Ex. 17 exhibited low roughness but also exhibited relatively high reflectance and light scattering, as shown above in Table 17.

TABLE 17 Abrasion resistance, as measured by AFM roughness statistics, after being subjected to the Taber Test, for Examples 12-13 and Comparative Examples 14, 17 and 18. AFM roughness (Ra, Std. Dev. (of Ra, Examples nm, 5 scan average) nm, 5 scans) Example 12 7.1 5.4 Example 13 3.5 2.9 Comp. Ex. 14 16.8 8.2 Comp. Ex. 17 4.5 0.7 Comp. Ex. 18 14.1 8.9

FIG. 34 is a graph showing the AFM roughness statistics from Table 22.

Example 19

Example 19 included a 10-layer anti-reflective coating disposed on a strengthened aluminosilicate glass substrate having a nominal composition of about 58 mol % SiO₂, 17 mol % Al₂O₃, 17 mol % Na₂O, 3 mol % MgO, 0.1 mol % SnO, and 6.5 mol % P₂O₅. The thicknesses of the layers are shown in Table 18.

Both SiO₂ and Si_(u)Al_(v)O_(x)N_(y) layers were made by reactive sputtering in a coater made by AJA Industries. SiO₂ was deposited by DC reactive sputtering from an Si target with ion assist; Si_(u)Al_(v)O_(x)N_(y) material was deposited by DC reactive sputtering combined with RF superimposed DC sputtering with ion assist. The reactive gasses were nitrogen and oxygen, and the “working” (or inert) gas was Argon.

TABLE 18 Attributes for Example 19. Peri- Refractive Physical Layer ods Material Index Thickness (nm) Ambient — Air 1 medium Anti- 1 SiO₂ 1.48623 96.75 reflective Si_(u)Al_(v)O_(x)N_(y) 2.03056 68.92 coating 2 SiO₂ 1.48623 24.13 Si_(u)Al_(v)O_(x)N_(y) 2.03056 36.64 3 SiO₂ 1.48623 70.12 Si_(u)Al_(v)O_(x)N_(y) 2.03056 28.12 4 SiO₂ 1.48623 23.54 Si_(u)Al_(v)O_(x)N_(y) 2.03056 110.49 5 SiO₂ 1.48623 31.23 Si_(u)Al_(v)O_(x)N_(y) 2.03056 16.82 Substrate — AS Glass 1.511 — Total Coating 506.75 nm Thickness

The amount of high RI material is about 51.5% and the amount of low RI material is about 48.5% of the anti-reflective coating. The deposition conditions are shown in Table 19. The deposition temperature was 200° C. and

TABLE 19 Deposition recipe for Example 19. Dep. Ar N2 O2 Time flow flow flow Al Al Si Si P Periods Material (seconds) (sccm) (sccm) (sccm) Wrf Wdc Wrf shutter (torr) 1 SiO₂ 1248 200 30 30 3.3  50  75 500 1 Si_(u)Al_(v)O_(x)N_(y)  633 200 30 30 0.5 200 300 500 1 2 SiO₂  318 200 30 30 3.3  50  75 500 1 Si_(u)Al_(v)O_(x)N_(y)  235 200 30 30 0.5 200 300 500 1 3 SiO₂ 1011 200 30 30 3.3  50  75 500 1 Si_(u)Al_(v)O_(x)N_(y)  179 200 30 30 0.5 200 300 500 1 4 SiO₂  305 200 30 30 3.3  50  75 500 1 Si_(u)Al_(v)O_(x)N_(y)  933 200 30 30 0.5 200 300 500 1 5 SiO₂  429 200 30 30 3.3  50  75 500 1 Si_(u)Al_(v)O_(x)N_(y)  121 200 30 30 0.5 200 300 500 1

The reflectance values of a single side of the article of Example 19 at different viewing incident illumination angles or angle of illumination (“AOI”) were modeled using the dispersion curves obtained for each of the coating materials and the glass substrate. The resulting modeled reflectance spectra is shown in FIG. 35. The reflected color and transmitted color, based on a 10° observer under a D65 illuminant and a F2 illuminant were also measured and the a* and b* values are plotted as the incident illumination angle or AOI changed from 0 degrees to about 60 degrees from normal incidence at regular increments. The plot showing both the reflected color and transmitted color for Example 19 is shown in FIG. 36. As shown in FIG. 36 and in Table 21 below, both the reflected and transmitted color are less than 3 from a*=0 and b*=0, for incident illumination angles from 0 degrees to about 60 degrees. Example 19 was evaluated for photopic reflectance at different AOI. From an AOI in the range from about 0° to about 20°, the photopic reflectance may be about 0.4 or less.

TABLE 21 Photopic reflectance, reflectance color shift, thickness and percentage of hard material for Example 19 and Comparative Example 11. % R (Photopic Refl. Color shift Avg., Y) 5-60 degrees Total (wavelengths (max-min, D65) thickness % Hard Ex. 450-650 nm) a* b* nm material Comparative 0.4 7.0 12.4 Example 11 Ex. 19 0.4 2.5 1.4 500 51

Example 20

Example 20 included a 10-layer anti-reflective coating disposed on a strengthened aluminosilicate glass substrate having a nominal composition of about 58 mol % SiO₂, 17 mol % Al₂O₃, 17 mol % Na₂O, 3 mol % MgO, 0.1 mol % SnO, and 6.5 mol % P₂O₅. The thicknesses of the layers are shown in Table 22.

The SiO₂ and Si_(u)Al_(v)O_(x)N_(y) layers were made by reactive sputtering in a coater made by Optorun Co. Ltd. SiO₂ was deposited by DC reactive sputtering from a Si target with ion assist; Si_(u)Al_(v)O_(x)N_(y) material was deposited by DC reactive sputtering combined with RF superimposed DC sputtering with ion assist. The reactive gasses were nitrogen and oxygen, and the “working” (or inert) gas was Argon. The deposition conditions for the SiO₂ and Si_(u)Al_(v)O_(x)N_(y) layers are provided in Table 23. Each layer was formed at 200° C. deposition temperature and for a deposition time sufficient to form the physical thickness of each layer.

TABLE 22 Attributes for Example 20. Peri- Refractive Physical Layer ods Material Index Thickness (nm) — Air 1 Anti- 1 SiO₂ 1.48114 89 reflective Si_(u)Al_(v)O_(x)N_(y) 2.00605 87.7 coating 2 SiO₂ 1.48114 21.9 Si_(u)Al_(v)O_(x)N_(y) 2.00605 27.6 3 SiO₂ 1.48114 72.9 Si_(u)Al_(v)O_(x)N_(y) 2.00605 23.7 4 SiO₂ 1.48114 22.9 Si_(u)Al_(v)O_(x)N_(y) 2.00605 114.9 5 SiO₂ 1.48114 30.2 Si_(u)Al_(v)O_(x)N_(y) 2.00605 15.6 Substrate — AS Glass 1.50542 — Total Coating Thickness 506.4 nm

TABLE 23 Deposition conditions for Example 20. N2 O2 Ar Flow flow flow Al Al Si Si P Layer (sccm) (sccm) (sccm) Wrf Wdc Wrf shutter (torr) Bias SiO₂ 30 30 3.3  50  75 500 1 4 0 Si_(u)Al_(v)O_(x)N_(y) 30 30 0.5 200 300 500 1 2 0

Example 20 exhibited a single side average reflectance (i.e., measured from the anti-reflective surface 122) over the optical wavelength regime at incident illumination angles of 0°, 30°, 45° and 60°, of 0.86%, 1.04%, 1.6%, and 3.61%, respectively. Example 20 exhibited a single side average transmittance (i.e., measured from the anti-reflective surface 122) over the optical wavelength regime at incident illumination angles of 0°, 30°, 45° and 60°, of 99.14%, 98.95%, 98.4%, and 96.39%, respectively.

Example 20 exhibited a total average reflectance (i.e., measured from the anti-reflective surface 122 and the opposite major surface 114) over the optical wavelength regime at incident illumination angles of 0°, 30°, 45° and 60°, of 4.85%, 3.56%, 2.44%, and 3.77%, respectively. Example 20 exhibited a single side average transmittance (i.e., measured from the anti-reflective surface 122) over the optical wavelength regime at incident illumination angles of 0°, 30°, 45° and 60°, of 95.15%, 96.44%, 97.56%, and 96.23%, respectively.

The reflectance and transmitted color coordinates for a single surface (i.e., anti-reflective surface 122) and two surfaces (i.e., anti-reflective surface 122 and major surface 114, of FIG. 1) of Example 20, under incident illumination angles or AOI from 0 degrees to 60 degrees (or 75 degrees) and illuminants D65 and F2 are shown in Tables 24A-24D. Single surface color coordinates were measured by eliminating transmission or reflectance from the major surface 114, as is known in the art. The color shift is calculated using the following equation: √((a*₂−a*₁)²+(b*₂−b*₁)²), with a*₁, and b*₁ representing the a* and b* coordinates of the article when viewed at normal incidence (i.e., AOI=0) and a*₂, and b*₂ representing the a* and b* coordinates of the article when viewed at an incident illumination angle different or away from normal incidence (i.e., AOI=1-60 or 1-75).

TABLE 24A One surface reflectance and transmitted color coordinates (Y, L*, a* and b*) using illuminant D65 for Example 20. Reflectance, D65 Transmittance, D65 AOI Y L* a* b* AOI Y L* a* b*  0 0.5366 4.8468 −2.8959 −1.6828  0 99.4622 99.7917 0.1231 0.0761  1 0.5365 4.8462 −2.8956 −1.681  1 99.4623 99.7917 0.1231 0.076  2 0.5363 4.8443 −2.8947 −1.6757  2 99.4625 99.7918 0.123 0.0758  3 0.5359 4.8412 −2.893 −1.667  3 99.4628 99.7919 0.123 0.0754  4 0.5355 4.8369 −2.8905 −1.6551  4 99.4633 99.7921 0.1228 0.0749  5 0.5349 4.8315 −2.8872 −1.6403  5 99.4639 99.7923 0.1227 0.0742  6 0.5342 4.8251 −2.8827 −1.6229  6 99.4646 99.7926 0.1225 0.0735  7 0.5334 4.8178 −2.8771 −1.6033  7 99.4654 99.7929 0.1223 0.0727  8 0.5325 4.8099 −2.87 −1.582  8 99.4663 99.7933 0.122 0.0717  9 0.5315 4.8014 −2.8612 −1.5596  9 99.4672 99.7936 0.1216 0.0708 10 0.5306 4.7926 −2.8506 −1.5366 10 99.4682 99.794 0.1211 0.0698 11 0.5296 4.7838 −2.8378 −1.5136 11 99.4692 99.7944 0.1206 0.0688 12 0.5286 4.7751 −2.8227 −1.4913 12 99.4701 99.7948 0.1199 0.0679 13 0.5277 4.7669 −2.8049 −1.4703 13 99.4711 99.7951 0.1192 0.067 14 0.5269 4.7596 −2.7842 −1.4513 14 99.4719 99.7954 0.1183 0.0661 15 0.5262 4.7534 −2.7604 −1.4351 15 99.4725 99.7957 0.1172 0.0655 16 0.5257 4.7488 −2.7333 −1.4223 16 99.4731 99.7959 0.1161 0.0649 17 0.5254 4.7463 −2.7026 −1.4136 17 99.4733 99.796 0.1148 0.0645 18 0.5254 4.7463 −2.6681 −1.4097 18 99.4733 99.796 0.1133 0.0644 19 0.5258 4.7495 −2.6297 −1.4113 19 99.473 99.7959 0.1116 0.0644 20 0.5266 4.7563 −2.5871 −1.4191 20 99.4722 99.7956 0.1098 0.0648 21 0.5278 4.7675 −2.5402 −1.4336 21 99.471 99.7951 0.1078 0.0654 22 0.5296 4.7839 −2.489 −1.4557 22 99.4691 99.7944 0.1056 0.0664 23 0.5321 4.8062 −2.4332 −1.4858 23 99.4667 99.7934 0.1032 0.0677 24 0.5353 4.8353 −2.373 −1.5245 24 99.4634 99.7922 0.1006 0.0694 25 0.5394 4.8723 −2.3081 −1.5726 25 99.4593 99.7906 0.0978 0.0714 26 0.5445 4.9182 −2.2386 −1.6304 26 99.4543 99.7886 0.0948 0.0739 27 0.5507 4.9742 −2.1645 −1.6986 27 99.4481 99.7862 0.0917 0.0769 28 0.5581 5.0416 −2.0858 −1.7777 28 99.4406 99.7833 0.0883 0.0803 29 0.567 5.122 −2.0025 −1.8682 29 99.4317 99.7798 0.0847 0.0842 30 0.5775 5.2169 −1.9148 −1.9705 30 99.4212 99.7758 0.0809 0.0886 31 0.5899 5.3281 −1.8227 −2.0851 31 99.4089 99.771 0.077 0.0935 32 0.6042 5.4577 −1.7263 −2.2123 32 99.3945 99.7654 0.0729 0.099 33 0.6208 5.6078 −1.6258 −2.3526 33 99.3779 99.7589 0.0685 0.1051 34 0.64 5.7808 −1.5214 −2.5062 34 99.3587 99.7515 0.0641 0.1117 35 0.662 5.9794 −1.4133 −2.6735 35 99.3367 99.743 0.0594 0.1189 36 0.6871 6.2066 −1.3016 −2.8546 36 99.3116 99.7332 0.0546 0.1268 37 0.7158 6.4657 −1.1867 −3.0459 37 99.2829 99.7221 0.0497 0.1352 38 0.7484 6.7603 −1.0688 −3.2299 38 99.2503 99.7094 0.0446 0.1443 39 0.7854 7.0945 −0.9482 −3.3995 39 99.2133 99.695 0.0395 0.1539 40 0.8273 7.4726 −0.8253 −3.548 40 99.1714 99.6787 0.0342 0.1642 41 0.8745 7.8997 −0.7003 −3.6678 41 99.1241 99.6603 0.0288 0.1751 42 0.9279 8.3754 −0.5592 −3.7604 42 99.0708 99.6396 0.0234 0.1866 43 0.9879 8.8899 −0.4162 −3.8434 43 99.0108 99.6162 0.0179 0.1988 44 1.0553 9.4441 −0.2829 −3.9167 44 98.9433 99.59 0.0123 0.2115 45 1.1311 10.0387 −0.16 −3.9793 45 98.8676 99.5605 0.0068 0.2247 46 1.216 10.6748 −0.0477 −4.0308 46 98.7826 99.5274 0.0012 0.2386 47 1.3111 11.3531 0.0537 −4.0708 47 98.6875 99.4903 −0.0044 0.253 48 1.4176 12.0745 0.1444 −4.099 48 98.581 99.4487 −0.0099 0.2679 49 1.5367 12.8397 0.2244 −4.1155 49 98.4619 99.4022 −0.0154 0.2833 50 1.6699 13.6496 0.2942 −4.1202 50 98.3287 99.3501 −0.0208 0.2993 51 1.8186 14.5047 0.3541 −4.1135 51 98.18 99.292 −0.0262 0.3157 52 1.9846 15.406 0.4047 −4.0957 52 98.014 99.227 −0.0315 0.3325 53 2.1698 16.3541 0.4466 −4.0673 53 97.8288 99.1543 −0.0367 0.3498 54 2.3764 17.3501 0.4805 −4.0288 54 97.6222 99.0732 −0.0419 0.3674 55 2.6068 18.3947 0.5072 −3.9809 55 97.3918 98.9826 −0.0469 0.3855 56 2.8635 19.4889 0.5273 −3.9242 56 97.135 98.8815 −0.0519 0.404 57 3.1497 20.6339 0.5416 −3.8593 57 96.8488 98.7685 −0.0568 0.4228 58 3.4686 21.8306 0.5508 −3.787 58 96.53 98.6424 −0.0616 0.4419 59 3.8239 23.0804 0.5556 −3.708 59 96.1747 98.5016 −0.0663 0.4614 60 4.2196 24.3845 0.5567 −3.6229 60 95.779 98.3443 −0.071 0.4812 Reflectance color shift Low: 0.0018 Transmittance color shift Low: 0.0001 range between normal High: 1.97861 range from normal High: 0.4492 incidence (AOI = 0 incidence (AOI = 0) to degrees) to AOI = 36 AOI = 60 degrees Reflectance color shift Low: 2.1861 range between normal High: 4.1114 incidence (AOI = 0 degrees) and AOI = 37- 60 degrees

TABLE 24B One surface reflectance and transmitted color coordinates (Y, L*, a* and b*) using illuminant F2 for Example 20. Reflectance, F2 Transmittance, F2 AOI Y L* a* b* AOI Y L* a* b*  0 0.4711 4.2557 −1.6317 −1.9631  0 99.5279 99.8172 0.0693 0.0885  1 0.4711 4.2552 −1.6304 −1.9618  1 99.5279 99.8172 0.0692 0.0884  2 0.4709 4.2538 −1.6264 −1.9583  2 99.5281 99.8172 0.069 0.0883  3 0.4707 4.2515 −1.6197 −1.9524  3 99.5283 99.8173 0.0687 0.088  4 0.4703 4.2482 −1.6104 −1.9443  4 99.5287 99.8175 0.0683 0.0877  5 0.4699 4.2443 −1.5983 −1.9342  5 99.5291 99.8176 0.0678 0.0872  6 0.4694 4.2397 −1.5835 −1.9224  6 99.5296 99.8178 0.0672 0.0867  7 0.4688 4.2346 −1.5659 −1.9091  7 99.5302 99.8181 0.0664 0.0862  8 0.4682 4.2291 −1.5454 −1.8946  8 99.5308 99.8183 0.0656 0.0855  9 0.4676 4.2236 −1.5221 −1.8792  9 99.5314 99.8185 0.0646 0.0849 10 0.467 4.2181 −1.4959 −1.8633 10 99.532 99.8188 0.0634 0.0842 11 0.4664 4.213 −1.4668 −1.8472 11 99.5326 99.819 0.0622 0.0835 12 0.4659 4.2086 −1.4348 −1.8314 12 99.5331 99.8192 0.0608 0.0828 13 0.4655 4.2051 −1.3999 −1.8161 13 99.5335 99.8193 0.0593 0.0822 14 0.4653 4.2031 −1.3621 −1.8019 14 99.5337 99.8194 0.0577 0.0816 15 0.4653 4.2027 −1.3216 −1.789 15 99.5337 99.8194 0.0559 0.081 16 0.4655 4.2046 −1.2783 −1.7778 16 99.5335 99.8193 0.0541 0.0805 17 0.466 4.2092 −1.2324 −1.7688 17 99.533 99.8191 0.0521 0.0802 18 0.4669 4.217 −1.184 −1.7622 18 99.5321 99.8188 0.05 0.0799 19 0.4681 4.2287 −1.1333 −1.7585 19 99.5308 99.8183 0.0479 0.0797 20 0.4699 4.2448 −1.0805 −1.758 20 99.529 99.8176 0.0456 0.0797 21 0.4723 4.2661 −1.0257 −1.7611 21 99.5267 99.8167 0.0432 0.0799 22 0.4753 4.2934 −0.9693 −1.7683 22 99.5237 99.8155 0.0408 0.0802 23 0.4791 4.3274 −0.9115 −1.78 23 99.5199 99.8141 0.0383 0.0807 24 0.4837 4.3692 −0.8526 −1.7966 24 99.5153 99.8123 0.0358 0.0814 25 0.4893 4.4197 −0.793 −1.8187 25 99.5097 99.8101 0.0332 0.0824 26 0.496 4.4801 −0.7328 −1.8468 26 99.503 99.8075 0.0307 0.0836 27 0.5039 4.5514 −0.6726 −1.8817 27 99.4951 99.8044 0.0281 0.0851 28 0.5131 4.6352 −0.6127 −1.9239 28 99.4858 99.8008 0.0255 0.0869 29 0.524 4.7328 −0.5534 −1.9742 29 99.475 99.7966 0.023 0.0891 30 0.5365 4.8458 −0.4952 −2.0334 30 99.4625 99.7918 0.0205 0.0917 31 0.5509 4.976 −0.4384 −2.1023 31 99.4481 99.7862 0.018 0.0947 32 0.5674 5.1253 −0.3835 −2.182 32 99.4315 99.7798 0.0157 0.0981 33 0.5863 5.2958 −0.3307 −2.2734 33 99.4126 99.7724 0.0134 0.102 34 0.6078 5.4899 −0.2806 −2.3774 34 99.3911 99.7641 0.0112 0.1065 35 0.6321 5.7101 −0.2335 −2.4952 35 99.3668 99.7546 0.0092 0.1116 36 0.6597 5.9593 −0.1897 −2.6277 36 99.3392 99.7439 0.0073 0.1174 37 0.6909 6.2406 −0.1497 −2.7761 37 99.308 99.7318 0.0056 0.1238 38 0.726 6.5575 −0.1138 −2.9365 38 99.2729 99.7182 0.0041 0.131 39 0.7654 6.9139 −0.0823 −3.0886 39 99.2335 99.7029 0.0027 0.1389 40 0.8097 7.314 −0.0556 −3.2243 40 99.1892 99.6856 0.0016 0.1477 41 0.8594 7.7626 −0.0341 −3.3366 41 99.1395 99.6663 0.0006 0.1573 42 0.915 8.262 −0.0175 −3.4219 42 99.0839 99.6447 −0.0001 0.1678 43 0.9772 8.7997 −0.007 −3.5027 43 99.0217 99.6205 −0.0005 0.1793 44 1.0467 9.3743 −0.0026 −3.5818 44 98.9522 99.5934 −0.0007 0.1917 45 1.1243 9.9866 −0.004 −3.6584 45 98.8746 99.5632 −0.0006 0.2051 46 1.2109 10.6374 −0.0105 −3.7314 46 98.788 99.5294 −0.0003 0.2196 47 1.3075 11.3276 −0.0214 −3.7999 47 98.6914 99.4918 0.0004 0.2351 48 1.4151 12.058 −0.0362 −3.863 48 98.5837 99.4498 0.0013 0.2517 49 1.5351 12.8295 −0.0542 −3.92 49 98.4637 99.4029 0.0025 0.2693 50 1.6687 13.6429 −0.0747 −3.97 50 98.3301 99.3507 0.0041 0.288 51 1.8176 14.4992 −0.0972 −4.0126 51 98.1812 99.2924 0.006 0.3077 52 1.9833 15.3994 −0.121 −4.0471 52 98.0155 99.2275 0.0081 0.3286 53 2.1678 16.3444 −0.1457 −4.0733 53 97.831 99.1552 0.0106 0.3505 54 2.3732 17.3352 −0.1706 −4.0907 54 97.6256 99.0745 0.0135 0.3735 55 2.6019 18.3731 −0.1953 −4.0992 55 97.397 98.9846 0.0166 0.3976 56 2.8564 19.4592 −0.2193 −4.0987 56 97.1424 98.8844 0.02 0.4227 57 3.1397 20.5949 −0.2424 −4.0891 57 96.8591 98.7726 0.0238 0.4488 58 3.4551 21.7814 −0.264 −4.0706 58 96.5437 98.6479 0.0278 0.476 59 3.8062 23.0202 −0.2839 −4.0431 59 96.1926 98.5087 0.0321 0.5041 60 4.1972 24.3129 −0.3019 −4.007 60 95.8016 98.3534 0.0366 0.5332 Reflectance color shift Low: 0.0018 Transmittance color shift Low: 0.0001 range between normal High: 1.9150 range from normal High: 0.4459 incidence (AOI = 0 incidence (AOI = 0) to degrees) to AOI = 39 AOI = 60 degrees Reflectance color shift Low: 2.1859 range between normal High: 2.5810 incidence (AOI = 0 degrees) and AOI = 40- 60 degrees

TABLE 24C Two surface reflectance and transmitted color coordinates (Y, L*, a* and b*) using illuminant D65 for Example 20. Reflectance, D65 Transmittance, D65 AOI Y L* a* b* AOI Y L* a* b*  0 4.5668 25.4632 −0.9446 −1.0023  0 95.4319 98.2061 0.1224 0.1381  1 4.5668 25.463 −0.9445 −1.0018  1 95.432 98.2061 0.1224 0.138  2 4.5666 25.4624 −0.9442 −1.0002  2 95.4322 98.2062 0.1224 0.1378  3 4.5663 25.4615 −0.9438 −0.9977  3 95.4325 98.2063 0.1223 0.1375  4 4.5658 25.4602 −0.943 −0.9942  4 95.4329 98.2065 0.1222 0.137  5 4.5653 25.4587 −0.942 −0.9898  5 95.4334 98.2067 0.1221 0.1364  6 4.5648 25.457 −0.9407 −0.9847  6 95.434 98.2069 0.1219 0.1357  7 4.5642 25.4553 −0.939 −0.9789  7 95.4345 98.2071 0.1216 0.1349  8 4.5636 25.4535 −0.9368 −0.9727  8 95.4351 98.2073 0.1213 0.134  9 4.5631 25.452 −0.9341 −0.966  9 95.4356 98.2076 0.121 0.1331 10 4.5627 25.4508 −0.9307 −0.9592 10 95.436 98.2077 0.1205 0.1322 11 4.5625 25.4501 −0.9267 −0.9524 11 95.4362 98.2078 0.12 0.1313 12 4.5625 25.4501 −0.9218 −0.9457 12 95.4362 98.2078 0.1194 0.1304 13 4.5628 25.451 −0.9161 −0.9395 13 95.4359 98.2077 0.1186 0.1295 14 4.5635 25.4532 −0.9094 −0.9337 14 95.4352 98.2074 0.1178 0.1288 15 4.5647 25.4568 −0.9016 −0.9288 15 95.434 98.2069 0.1168 0.1281 16 4.5665 25.4622 −0.8926 −0.9247 16 95.4322 98.2062 0.1156 0.1276 17 4.569 25.4697 −0.8824 −0.9219 17 95.4297 98.2052 0.1143 0.1273 18 4.5723 25.4798 −0.8708 −0.9203 18 95.4264 98.2039 0.1129 0.1271 19 4.5766 25.4927 −0.8578 −0.9203 19 95.4221 98.2022 0.1113 0.1272 20 4.582 25.5091 −0.8434 −0.922 20 95.4167 98.2 0.1095 0.1275 21 4.5887 25.5293 −0.8275 −0.9255 21 95.41 98.1973 0.1075 0.1282 22 4.5969 25.5539 −0.8099 −0.931 22 95.4018 98.1941 0.1053 0.1291 23 4.6067 25.5836 −0.7908 −0.9386 23 95.392 98.1901 0.103 0.1303 24 4.6184 25.6188 −0.77 −0.9484 24 95.3802 98.1855 0.1004 0.1319 25 4.6323 25.6605 −0.7475 −0.9606 25 95.3664 98.1799 0.0977 0.1338 26 4.6486 25.7092 −0.7234 −0.9751 26 95.3501 98.1734 0.0947 0.1361 27 4.6675 25.7658 −0.6976 −0.9922 27 95.3311 98.1659 0.0916 0.1389 28 4.6895 25.8313 −0.6702 −1.0117 28 95.3092 98.1571 0.0882 0.142 29 4.7149 25.9065 −0.6412 −1.0336 29 95.2838 98.147 0.0847 0.1456 30 4.7439 25.9924 −0.6106 −1.058 30 95.2547 98.1353 0.0809 0.1496 31 4.7772 26.0903 −0.5786 −1.0847 31 95.2215 98.1221 0.077 0.1541 32 4.8151 26.2013 −0.5451 −1.1137 32 95.1836 98.1069 0.0729 0.159 33 4.8581 26.3265 −0.5104 −1.1447 33 95.1406 98.0897 0.0686 0.1644 34 4.9068 26.4675 −0.4744 −1.1775 34 95.0919 98.0703 0.0641 0.1702 35 4.9618 26.6256 −0.4374 −1.2119 35 95.0369 98.0483 0.0595 0.1765 36 5.0238 26.8023 −0.3995 −1.2476 36 94.9749 98.0235 0.0547 0.1832 37 5.0934 26.9993 −0.3608 −1.2842 37 94.9052 97.9956 0.0498 0.1903 38 5.1716 27.2182 −0.3217 −1.3213 38 94.827 97.9643 0.0447 0.1979 39 5.2592 27.4608 −0.2821 −1.3584 39 94.7394 97.9292 0.0395 0.2058 40 5.3571 27.7289 −0.2424 −1.395 40 94.6415 97.8899 0.0342 0.214 41 5.4665 28.0244 −0.2029 −1.4306 41 94.5321 97.846 0.0288 0.2225 42 5.5884 28.3493 −0.1636 −1.4645 42 94.4102 97.797 0.0234 0.2313 43 5.7242 28.7057 −0.1249 −1.4961 43 94.2744 97.7424 0.0178 0.2403 44 5.8753 29.0956 −0.0869 −1.5249 44 94.1233 97.6817 0.0122 0.2494 45 6.0431 29.521 −0.0499 −1.5501 45 93.9554 97.614 0.0065 0.2585 46 6.2295 29.9842 −0.0142 −1.5712 46 93.7691 97.5389 0.0008 0.2676 47 6.4362 30.4872 0.0202 −1.5877 47 93.5624 97.4554 −0.0049 0.2767 48 6.6652 31.0322 0.0531 −1.5989 48 93.3334 97.3627 −0.0106 0.2855 49 6.9188 31.6213 0.0842 −1.6044 49 93.0798 97.26 −0.0164 0.2941 50 7.1993 32.2565 0.1136 −1.6038 50 92.7992 97.146 −0.0222 0.3023 51 7.5096 32.9399 0.141 −1.5968 51 92.489 97.0198 −0.028 0.3101 52 7.8523 33.6733 0.1666 −1.5833 52 92.1462 96.88 −0.0338 0.3174 53 8.2307 34.4588 0.1902 −1.563 53 91.7678 96.7253 −0.0397 0.324 54 8.6483 35.2981 0.2118 −1.5361 54 91.3502 96.554 −0.0456 0.3298 55 9.1088 36.1929 0.2317 −1.5027 55 90.8897 96.3646 −0.0516 0.3349 56 9.6163 37.1447 0.2497 −1.4629 56 90.3822 96.1551 −0.0577 0.339 57 10.1752 38.1551 0.2659 −1.4172 57 89.8232 95.9234 −0.0639 0.3422 58 10.7904 39.2253 0.2806 −1.366 58 89.208 95.6673 −0.0703 0.3443 59 11.4672 40.3565 0.2937 −1.3099 59 88.5312 95.3842 −0.0769 0.3453 60 12.2111 41.5497 0.3055 −1.2493 60 87.7873 95.0713 −0.0837 0.3451 61 13.1957 43.0567 −0.2359 −0.5057 61 86.8042 94.6551 0.0663 0.1464 62 14.0946 44.3683 −0.2259 −0.4794 62 85.9053 94.2719 0.0669 0.146 63 15.0802 45.7439 −0.2148 −0.4519 63 84.9197 93.8485 0.067 0.1451 64 16.16 47.1837 −0.2024 −0.4234 64 83.8399 93.3809 0.0667 0.1435 65 17.3418 48.6879 −0.1889 −0.3943 65 82.6581 92.8645 0.0658 0.1414 66 18.634 50.2563 −0.1743 −0.3648 66 81.3659 92.2943 0.0644 0.1387 67 20.0454 51.8886 −0.1589 −0.3353 67 79.9545 91.6644 0.0623 0.1355 68 21.5851 53.584 −0.1428 −0.306 68 78.4148 90.9689 0.0595 0.1316 69 23.2625 55.3417 −0.1262 −0.2772 69 76.7374 90.2006 0.056 0.1272 70 25.0872 57.1602 −0.1093 −0.2493 70 74.9128 89.3521 0.0518 0.1223 71 27.0688 59.038 −0.0924 −0.2223 71 72.9311 88.4148 0.0468 0.1169 72 29.2172 60.9728 −0.0758 −0.1966 72 70.7827 87.3793 0.041 0.111 73 31.5415 62.9622 −0.0596 −0.1722 73 68.4584 86.2351 0.0346 0.1048 74 34.0508 65.0029 −0.0443 −0.1495 74 65.9491 84.9704 0.0275 0.0983 75 36.7532 67.0914 −0.03 −0.1284 75 63.2467 83.572 0.0199 0.0916 Reflectance color shift Low: 0.0005 Transmittance color Low: 0.0001 range between normal High: 1.2800 shift range from normal High: 0.2921 incidence (AOI = 0 incidence (AOI = 0) to degrees) to AOI = 75 AOI = 75 degrees

TABLE 24D Two surface reflectance and transmitted color coordinates (Y, L*, a* and b*) using illuminant F2 for Example 20. Reflectance, F2 Transmittance, F2 AOI Y L* a* b* AOI Y L* a* b*  0 4.4977 25.2528 −0.5382 −1.1683  0 95.5013 98.2337 0.0691 0.1594  1 4.4976 25.2527 −0.5378 −1.1679  1 95.5013 98.2338 0.0691 0.1594  2 4.4975 25.2522 −0.5366 −1.1668  2 95.5015 98.2338 0.0689 0.1592  3 4.4972 25.2515 −0.5345 −1.1651  3 95.5017 98.2339 0.0686 0.159  4 4.4969 25.2506 −0.5316 −1.1627  4 95.502 98.234 0.0682 0.1587  5 4.4966 25.2495 −0.5278 −1.1598  5 95.5024 98.2342 0.0678 0.1583  6 4.4962 25.2484 −0.5232 −1.1563  6 95.5027 98.2343 0.0671 0.1578  7 4.4958 25.2473 −0.5177 −1.1523  7 95.5031 98.2345 0.0664 0.1572  8 4.4955 25.2463 −0.5113 −1.148  8 95.5034 98.2346 0.0656 0.1567  9 4.4953 25.2457 −0.5039 −1.1435  9 95.5036 98.2347 0.0646 0.156 10 4.4953 25.2455 −0.4957 −1.1387 10 95.5037 98.2347 0.0636 0.1554 11 4.4954 25.2459 −0.4865 −1.1339 11 95.5035 98.2346 0.0624 0.1548 12 4.4959 25.2473 −0.4764 −1.129 12 95.5031 98.2345 0.0611 0.1541 13 4.4967 25.2497 −0.4653 −1.1244 13 95.5023 98.2341 0.0596 0.1535 14 4.4979 25.2536 −0.4533 −1.1199 14 95.501 98.2336 0.0581 0.1529 15 4.4997 25.2591 −0.4404 −1.1158 15 95.4992 98.2329 0.0564 0.1524 16 4.5022 25.2666 −0.4265 −1.112 16 95.4968 98.2319 0.0547 0.152 17 4.5054 25.2765 −0.4118 −1.1088 17 95.4935 98.2306 0.0528 0.1516 18 4.5095 25.2891 −0.3963 −1.1062 18 95.4894 98.229 0.0508 0.1514 19 4.5147 25.3049 −0.38 −1.1043 19 95.4842 98.2269 0.0487 0.1512 20 4.5211 25.3243 −0.363 −1.1031 20 95.4778 98.2244 0.0465 0.1512 21 4.5288 25.3479 −0.3453 −1.1028 21 95.4701 98.2213 0.0443 0.1514 22 4.5382 25.3763 −0.3271 −1.1034 22 95.4608 98.2176 0.042 0.1517 23 4.5492 25.4099 −0.3084 −1.1051 23 95.4497 98.2132 0.0396 0.1522 24 4.5623 25.4495 −0.2893 −1.1078 24 95.4366 98.2079 0.0372 0.1528 25 4.5776 25.4957 −0.27 −1.1117 25 95.4213 98.2018 0.0347 0.1537 26 4.5954 25.5494 −0.2505 −1.1169 26 95.4035 98.1947 0.0322 0.1548 27 4.616 25.6114 −0.231 −1.1235 27 95.3829 98.1865 0.0298 0.1562 28 4.6396 25.6824 −0.2116 −1.1315 28 95.3592 98.1771 0.0273 0.1579 29 4.6668 25.7636 −0.1925 −1.1411 29 95.3321 98.1662 0.0249 0.1598 30 4.6978 25.8558 −0.1737 −1.1524 30 95.3011 98.1539 0.0225 0.1621 31 4.733 25.9601 −0.1555 −1.1654 31 95.2659 98.1398 0.0201 0.1648 32 4.7729 26.0778 −0.1379 −1.1802 32 95.2259 98.1238 0.0179 0.1678 33 4.8181 26.2101 −0.1211 −1.1969 33 95.1808 98.1058 0.0157 0.1713 34 4.869 26.3582 −0.1052 −1.2155 34 95.1299 98.0855 0.0136 0.1752 35 4.9262 26.5235 −0.0903 −1.236 35 95.0726 98.0626 0.0117 0.1795 36 4.9905 26.7076 −0.0765 −1.2584 36 95.0084 98.0369 0.0098 0.1844 37 5.0624 26.9118 −0.064 −1.2826 37 94.9364 98.0081 0.0082 0.1897 38 5.1429 27.138 −0.0527 −1.3084 38 94.856 97.9759 0.0067 0.1956 39 5.2327 27.3877 −0.0428 −1.3356 39 94.7661 97.9399 0.0053 0.2021 40 5.3328 27.6627 −0.0342 −1.364 40 94.666 97.8997 0.0041 0.2091 41 5.4443 27.9649 −0.0271 −1.3933 41 94.5545 97.855 0.0031 0.2166 42 5.5683 28.2961 −0.0214 −1.423 42 94.4305 97.8052 0.0023 0.2246 43 5.706 28.6582 −0.0171 −1.4526 43 94.2928 97.7499 0.0017 0.2332 44 5.8588 29.0534 −0.0141 −1.4817 44 94.14 97.6884 0.0013 0.2423 45 6.0282 29.4836 −0.0124 −1.5097 45 93.9706 97.6201 0.0011 0.2518 46 6.216 29.9509 −0.0119 −1.5359 46 93.7828 97.5444 0.001 0.2616 47 6.4238 30.4573 −0.0124 −1.5597 47 93.575 97.4605 0.0012 0.2719 48 6.6536 31.0051 −0.0138 −1.5805 48 93.3451 97.3675 0.0015 0.2823 49 6.9078 31.5961 −0.0159 −1.5976 49 93.091 97.2645 0.0019 0.293 50 7.1886 32.2326 −0.0185 −1.6105 50 92.8101 97.1505 0.0024 0.3037 51 7.4988 32.9164 −0.0215 −1.6184 51 92.5 97.0243 0.0031 0.3145 52 7.8411 33.6497 −0.0247 −1.621 52 92.1577 96.8847 0.0038 0.3251 53 8.2187 34.4343 −0.0278 −1.6178 53 91.78 96.7303 0.0046 0.3355 54 8.6351 35.2721 −0.0306 −1.6084 54 91.3636 96.5596 0.0054 0.3455 55 9.0941 36.1648 −0.0329 −1.5926 55 90.9046 96.3708 0.0061 0.3551 56 9.5996 37.1141 −0.0346 −1.5703 56 90.3991 96.1621 0.0068 0.364 57 10.1563 38.1215 −0.0354 −1.5414 57 89.8424 95.9314 0.0073 0.3723 58 10.7689 39.1884 −0.0353 −1.5062 58 89.2298 95.6764 0.0077 0.3797 59 11.4426 40.3162 −0.0341 −1.4648 59 88.5561 95.3946 0.0078 0.3861 60 12.1832 41.5059 −0.0318 −1.4175 60 87.8154 95.0832 0.0075 0.3915 61 13.191 43.0497 −0.3225 −0.5066 61 86.8089 94.6571 0.0912 0.1466 62 14.0869 44.3573 −0.3206 −0.4919 62 85.913 94.2752 0.0954 0.1498 63 15.0693 45.7289 −0.316 −0.4754 63 84.9307 93.8532 0.0992 0.1525 64 16.1456 47.1649 −0.309 −0.4571 64 83.8543 93.3872 0.1024 0.1548 65 17.3238 48.6655 −0.2996 −0.437 65 82.6761 92.8725 0.1051 0.1566 66 18.6124 50.2306 −0.288 −0.4155 66 81.3876 92.3039 0.1071 0.1577 67 20.02 51.8599 −0.2744 −0.3926 67 79.9799 91.6758 0.1084 0.1583 68 21.556 53.5527 −0.259 −0.3686 68 78.444 90.9821 0.1089 0.1581 69 23.2297 55.3082 −0.2422 −0.3438 69 76.7702 90.2157 0.1086 0.1573 70 25.051 57.1251 −0.2243 −0.3184 70 74.949 89.3691 0.1074 0.1557 71 27.0295 59.0016 −0.2055 −0.2928 71 72.9705 88.4336 0.1053 0.1533 72 29.1749 60.9357 −0.1861 −0.2672 72 70.825 87.3999 0.1024 0.1503 73 31.4968 62.9248 −0.1666 −0.242 73 68.5031 86.2574 0.0986 0.1465 74 34.0041 64.9658 −0.1473 −0.2173 74 65.9959 84.9943 0.094 0.142 75 36.7049 67.0551 −0.1284 −0.1934 75 63.295 83.5974 0.0886 0.1369 Reflectance color shift Low: 0.0005 Transmittance color shift Low: 0.0001 range between normal High: 1.0575 range from normal High: 0.2401 incidence (AOI = 0 degrees) incidence (AOI = 0) to to AOI = 75 degrees AOI = 75

Example 21

Example 21 included a 10-layer anti-reflective coating disposed on a strengthened aluminosilicate glass substrate having a nominal composition of about 58 mol % SiO₂, 17 mol % Al₂O₃, 17 mol % Na₂O, 3 mol % MgO, 0.1 mol % SnO, and 6.5 mol % P₂O₅. The thicknesses of the layers are shown in Table 25.

The SiO₂ and AlO_(x)N_(y) layers were made by reactive sputtering in a coater made by Optorun Co. Ltd. SiO₂ was deposited by DC reactive sputtering from a Si target with ion assist; AlO_(x)N_(y) material was deposited by DC reactive sputtering combined with RF superimposed DC sputtering with ion assist. The reactive gasses were nitrogen and oxygen, and the “working” (or inert) gas was Argon. The deposition conditions for the SiO₂ and AlO_(x)N_(y) layers are provided in Table 26. Each layer was formed at 200° C. deposition temperature and for a deposition time sufficient to form the physical thickness of each layer.

TABLE 25 Example 21 physical attributes. Refractive Physical Layer Material Index Thickness (nm) Medium Air 1 1 SiO₂ 1.47225 86.51 2 AlOxNy 1.98593 93.71 3 SiO₂ 1.47225 23.29 4 AlOxNy 1.98593 26.79 5 SiO₂ 1.47225 75.47 6 AlOxNy 1.98593 23.06 7 SiO₂ 1.47225 24.12 8 AlOxNy 1.98593 122.78 9 SiO₂ 1.47225 33.64 10  AlOxNy 1.98593 17.32 Substrate Glass 1.50542 Total coating 526.68 nm Thickness

TABLE 26 Deposition conditions for Example 21. Ar N2 O2 Flow flow flow Al Al Si Si P Layer (sccm) (sccm) (sccm) Wrf Wdc Wrf shutter (torr) Bias SiO₂ AlO_(x)N_(y)

The transmittance color coordinates at normal incidence were measured through both the anti-reflective surface of Example 21 and the opposite bare surface of Example 21 using a D65 illuminant, as shown in FIG. 37 and indicated by T(D65). The reflectance color coordinates were measured on the anti-reflective surface only using a F2 illuminant and at incident illumination angles of 20 degrees, 40 degrees and 60 degrees and a reference illumination angle of 6 degrees are also plotted in FIG. 37, and indicated by R(F2). The measured transmittance and reflectance color coordinates of the substrate are plotted in FIG. 37 and indicated by T(glass) and R(glass), respectively. As shown in FIG. 37, the transmittance color shift of the article with respect to the transmittance color coordinates of the substrate is very low (i.e., less than about 0.5). The color shift with respect to viewing angle in reflectance between the reference illumination angle (a*=−0.53, b*=2.08) and incident viewing angles 20 degrees (a*=−0.9, b*=1.95), 40 degrees (a*=−1.7, b*=0.69) and 60 degrees (a*=−0.44, b*=−1.89) was 0.39, 1.81 and 3.96, respectively.

FIG. 38 shows the reflectance spectra of Example 21 as measured on only the anti-reflective surface at the reference illumination angle and the incident viewing angles of 20 degrees, 40 degrees and 60 degrees. The radiometric and photopic average of Example 21 was calculated as 0.54%. The transmittance and reflectance spectra measured at the reference illumination angle (6 degrees) for both the anti-reflective surface and the opposite bare surface are shown in FIG. 39.

The measured hardness and the Young's modulus of Example 21, as measured on the anti-reflective surface, was 11.1 GPa and 110 GPa, respectively. Examples of Modeled Comparative Example 11 exhibited a hardness of about 6.8 GPa.

It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the invention. 

What is claimed is:
 1. An anti-reflective article comprising: a substrate having a major surface; and an anti-reflective coating having a thickness of about 0.2 μm to about 1 μm disposed on the major surface, the anti-reflective coating comprising an anti-reflective surface, wherein the anti-reflective coating comprises a plurality of layers, the plurality of layers comprising at least one low refractive index (RI) layer and at least one high RI layer, and wherein a total physical thickness of the high RI layers is greater than 28% of the total physical thickness of the anti-reflective coating, wherein the at least one low RI layer includes one low RI layer disposed on the major surface of the substrate, the one low RI layer has a physical thickness of greater than 10 nm to less than 150 nm, and wherein the article exhibits a maximum hardness of about 8 GPa or greater as measured by a Berkovich Indenter Hardness Test along an indentation depth of about 50 nm or greater.
 2. The article of claim 1, wherein each high RI layer comprises Si₃N₄, SiN_(x), SiO_(x)N_(y), or Si_(u)Al_(y)O_(x)N_(y).
 3. The article of claim 1, wherein the one low RI layer is in contact with the major surface of the substrate
 4. The article of claim 1, wherein the substrate comprises a glass selected from the group consisting of soda lime glass, alkali aluminosilicate glass, alkali containing borosilicate glass and alkali aluminoborosilicate glass.
 5. The article of claim 1, wherein the substrate is a crystalline substrate or a glass ceramic substrate.
 6. The article of claim 1, wherein the article exhibits either one or both: article transmittance color coordinates in the (L*, a*, b*) colorimetry system at normal incidence the D65 or F2 illuminant exhibiting a reference point color shift of less than about 2 from a reference point as measured at the anti-reflective surface, the reference point comprising at least one of the color coordinates (a*=0, b*=0) and the transmittance color coordinates of the substrate, and article reflectance color coordinates in the (L*, a*, b*) colorimetry system at normal incidence exhibiting a color shift of less than about 5 from a reference point as measured at the anti-reflective surface, the reference point comprising at least one of the color coordinates (a*=0, b*=0), the coordinates (a*=−2, b*=−2), and the reflectance color coordinates of the substrate, wherein, when the reference point is the color coordinates (a*=0, b*=0), the color shift is defined by √((a*_(article))²+(b*_(article))²), wherein, when the reference point is the color coordinates (a*=−2, b*=−2), the color shift is defined by √((a*_(article)+2)²+(b*_(article)+2)²), and wherein, when the reference point is the color coordinates of the substrate, the color shift is defined by √((a*_(article)−a*_(substrate))²+(b*_(article)−b*_(substrate))²).
 7. The article of claim 1, wherein the article exhibits an abrasion resistance comprising any one of: about 1% haze or less, as measured using a hazemeter having an aperture, wherein the aperture has a diameter of about 8 mm, an average roughness Ra, as measured by atomic force microscopy, of about 12 nm or less, a scattered light intensity of about 0.05 (in units of 1/steradian) or less, at a polar scattering angle of about 40 degrees or less, as measured at normal incidence in transmission using an imaging sphere for scatter measurements, with a 2 mm aperture at 600 nm wavelength, a scattered light intensity of about 0.1 (in units of 1/steradian) or less, at a polar scattering angle of about 20 degrees or less, as measured at normal incidence in transmission using an imaging sphere for scatter measurements, with a 2 mm aperture at 600 nm wavelength, wherein the abrasion resistance is measured after a 500-cycle abrasion using a Taber Test.
 8. An electronic product incorporating the article according to claim 1, wherein the article is a cover article configured to: (a) protect devices within the product, (b) provide a user interface for input, and/or (c) provide a display.
 9. An article comprising: a substrate having a major surface; and an anti-reflective coating having a physical thickness of from about 0.2 μm to about 1 μm disposed on the major surface, the anti-reflective coating comprising an anti-reflective surface, wherein the anti-reflective coating comprises a plurality of layers, the plurality of layers comprising at least one low refractive index (RI) layer and at least one high RI layer, and wherein a total physical thickness of the high RI layers is greater than 30% of the total physical thickness of the anti-reflective coating, wherein each high RI layer comprises Si₃N₄, SiN_(x), SiO_(x)N_(y), or Si_(u)Al_(v)O_(x)N_(y), wherein the at least one low RI layer includes one low RI layer of SiO₂ disposed on and in direct contact with the major surface of the substrate has a physical thickness of greater than 10 nm and less than 150 nm, wherein each low RI layer has a refractive index from about 1.3 to about 1.7 and each high RI layer has a refractive index of greater than about 1.7, wherein the article exhibits a maximum hardness of about 8 GPa or greater as measured by a Berkovich Indenter Hardness Test along an indentation depth of about 50 nm or greater.
 10. The article of claim 9, the anti-reflective coating comprises five (5) layers to seven (7) layers
 11. The article of claim 9, wherein the substrate is a crystalline substrate or a glass ceramic substrate.
 12. An electronic product incorporating the article according to claim 9, wherein the article is a cover article configured to: (a) protect devices within the product, (b) provide a user interface for input, and/or (c) provide a display.
 13. An article comprising: a substrate having a major surface; and an anti-reflective coating having a physical thickness of from about 0.2 μm to about 1 μm disposed on the major surface, the anti-reflective coating comprising an anti-reflective surface, wherein the anti-reflective coating comprises a plurality of alternating low and high refractive index layers that ranges from five (5) layers to seven (7) layers and comprises a first low refractive index (RI) layer of SiO₂ disposed on and in direct contact with the major surface, at least one additional low RI layer of SiO₂, and wherein a total physical thickness of the high RI layers is greater than about 30% of the total physical thickness of the anti-reflective coating, wherein each high RI layer comprises Si₃N₄, SiN_(x), SiO_(x)N_(y), or Si_(u)Al_(v)O_(x)N_(y), wherein the first low RI layer of SiO₂ disposed on and in direct contact with the major surface of the substrate has an optical thickness from about 15 nm to about 200 nm, wherein each low RI layer has a refractive index from about 1.3 to about 1.7 and each high RI layer has a refractive index of greater than about 1.9, and, wherein the article exhibits a maximum hardness of about 8 GPa or greater as measured by a Berkovich Indenter Hardness Test along an indentation depth of about 50 nm or greater.
 14. The article of claim 13, wherein a total physical thickness of the high RI layers is ≥200 nm.
 15. The article of claim 13, wherein the anti-reflective coating has a physical thickness of from about 350 nm to about 1 μm.
 16. The article of claim 13, wherein the anti-reflective coating has a physical thickness from about 0.2 μm to about 325 nm.
 17. The article of claim 13, wherein the substrate comprises a glass-ceramic substrate.
 18. The article of claim 13, wherein the article exhibits either one or both: article transmittance color coordinates in the (L*, a*, b*) colorimetry system at normal incidence the D65 or F2 illuminant exhibiting a reference point color shift of less than about 2 from a reference point as measured at the anti-reflective surface, the reference point comprising at least one of the color coordinates (a*=0, b*=0) and the transmittance color coordinates of the substrate, and article reflectance color coordinates in the (L*, a*, b*) colorimetry system at normal incidence exhibiting a color shift of less than about 5 from a reference point as measured at the anti-reflective surface, the reference point comprising at least one of the color coordinates (a*=0, b*=0), the coordinates (a*=−2, b*=−2), and the reflectance color coordinates of the substrate, wherein, when the reference point is the color coordinates (a*=0, b*=0), the color shift is defined by √((a*_(article))²+(b*_(article))²), wherein, when the reference point is the color coordinates (a*=−2, b*=−2), the color shift is defined by √((a*_(article)+2)²+(b*_(article)+2)²), and wherein, when the reference point is the color coordinates of the substrate, the color shift is defined by √((a*_(article)−a*_(substrate))²+(b*_(article)−b*_(substrate))²).
 19. The article of claim 13, wherein the article exhibits an abrasion resistance comprising any one of: about 1% haze or less, as measured using a hazemeter having an aperture, wherein the aperture has a diameter of about 8 mm, an average roughness Ra, as measured by atomic force microscopy, of about 12 nm or less, a scattered light intensity of about 0.05 (in units of 1/steradian) or less, at a polar scattering angle of about 40 degrees or less, as measured at normal incidence in transmission using an imaging sphere for scatter measurements, with a 2 mm aperture at 600 nm wavelength, a scattered light intensity of about 0.1 (in units of 1/steradian) or less, at a polar scattering angle of about 20 degrees or less, as measured at normal incidence in transmission using an imaging sphere for scatter measurements, with a 2 mm aperture at 600 nm wavelength, wherein the abrasion resistance is measured after a 500-cycle abrasion using a Taber Test.
 20. An electronic product incorporating the article according to claim 13, wherein the article is a cover article configured to: (a) protect devices within the product, (b) provide a user interface for input, and/or (c) provide a display. 